Mos burger is a Japanese fast food chain which offers Asian-style fast food. Instead of hamburger buns, several of their “hamburgers” are enclosed by rice pressed into a bun shape. When I was in Taiwan, I went a to baseball game; Mos burger was one of the stands in the stadium so I got to try them. I was disappointed in the taste of their fillings, but I was captivated by the idea of a rice bun for a hamburger, so I wanted to make my own version.
My “onigiri burger” or “rice burger” is loosely inspired by Mos burger; however the flavorings are quite different than what Mos burger offers and I chose to season my rice with furikake, which is a Japanese condiment that is often sprinkled on top of rice. These onigiri burgers are a messy but fun and satisfying dish.
The recipe below offers two variations: one made with a hamburger patty and one made with thinly sliced leftover roast pork. You could also experiment with other meats or fillings–Mos burger offers several options too (chicken, fish, pork, beef). The hamburger patty tastes somewhat similar in spirit to loco moco, the Hawaiian dish of white rice, topped with a hamburger, fried egg, and brown gravy but with furikake seasoning and no gravy. Roast pork slices taste similar to a breakfast sandwich because of the combination of salty pan-fried pork and eggs.
Despite how long the recipe looks, if you have left over hamburger patties or roast pork, this recipe is actually quick to assemble. You can make the furikake and toasted bonito flakes while the rice is cooking, and then all that’s left to do is to form the rice buns, fry some eggs, warm up the meat, and assemble everything.
Source: My own
Onigiri Burger (rice burger)
Onigiri Burger (rice burger):
- 2 cooked burgers (each made from about 1/4 lbs) of meat or enough leftover pork shoulder roast for 2 sandwiches
- kewpie mayonaise
- 1.5 g bonito flakes (a few tablespoons)
- 1 rice cooker measurement (3/4 cup) of raw Japanese short grained rice
Furikake (Ingredients that will be mixed with the rice):
- 1/2 sheet of nori
- 1 tsp aonori
- 1 Tbsp toasted brown or white sesame seeds (See here for how to toast sesame seeds. Wait until they are cool before adding them to the mixture)
- 1/2 tsp umami dust (recipe below)
- 1/8 tsp shichimi tōgarashi
- 1/2 tsp Diamond Crystal kosher salt
- plastic wrap
- (optional) rice cooker
Mix the Furikake:
Re-crisp nori by briefly passing it over a flame if the package has been open for a while and the nori is no longer crisp.
To cut nori into slivers (1/2 inch long or shorter): Using scissors, cut nori into long thin strips about 1/2-inch wide or thinner. Stack the strips and cut crosswise into thin strips.
Mix the nori and the rest of the furikake ingredients together in a container with a lid. Store tightly covered in order to keep the nori crisp.
Variation: Many premixed furikake mixtures are sold in Japanese grocery stores. If you don’t want to make your own, one of these could probably successfully be substituted for this mix. Choose one with compatible flavors and check labels to make sure that it doesn’t have any additives or preservatives that you don’t want. If the premixed furikake mixture that doesn’t have salt, add 1/2 tsp Diamond Crystal kosher salt to the rice in addition to the furikake.)
Variation: The onigiri burger would probably also taste fine with no furikake, though I haven’t tried this variation yet. If you choose to make this version, mix the cooked rice with 1/2 tsp Diamond Crystal kosher salt before forming the buns.
Toast bonito flakes:
The bonito flakes can be optionally toasted; toasting them helps to bring out their fragrance. Toast some bonito flakes on medium in a dry un-oiled pan, stirring constantly, until fragrant (it should only take a minute or two). Let cool and then store in a tightly covered container to keep crisp.
Cook the rice using your preferred rice cooking method (stovetop or rice cooker machine). Once the rice is done, use a rice paddle or large spoon to fluff the rice. You can leave it on the warmer setting if you are not ready to form the patties yet. (Don’t mix the furikake into the rice until just before forming the patties so that the furikake stays crisp.)
Cut four pieces of plastic wrap which are approximately 11 inch by 11 inches.
When you are ready to form the patties, use a silicone rice paddle or a large spoon which is slightly dampened with water to prevent sticking, mix the rice with the furikake. Use a 1-cup measure or preferably a scale to divide the rice into 4 equal portions.
If you can form the rice disks quickly (the rice should still be warm when you form it), then place each portion of rice on to a piece of plastic wrap. Otherwise place one portion of rice on a piece of plastic wrap and leave the remaining portions in your rice cooker (use the “keep warm” setting if it has it, otherwise just keep the lid on).
The rice buns are formed using the same techniques as onigiri. Two methods are described below. I recommend forming them with your hands — it is much easier than it sounds. The rice shouldn’t stick to your hands if they are damp and if you rinse off the excess starch in between forming disks. Use the plastic wrap method if you have trouble with the rice sticking.
To form each rice disk with your hands: Wet your hands with water, shake off the excess, and form the buns directly with your hands (the moisture will prevent the rice from sticking to your hands). Place each formed rice disk on top of a piece of plastic wrap. Rinse your hands to remove any excess starch sticking to them (no soap needed) and then form the next disk.
To form each rice disk using plastic wrap: If the rice is too hot to hold, you can wait a few seconds for it to cool down before forming it. The rice should be warm when you form it. To form, gently hold the rice in the plastic wrap, and squeeze the edges towards the middle to make them stick more firmly together. The rice will have formed a loose ball. Loosely enclose the rice in the plastic wrap and place on a counter or plate. Press flat into a disk. If necessary loosen the plastic wrap by lifting it up and re-draping over the rice. Alternate between gently pressing the edges into a circle shape, loosening the plastic wrap, and pressing flat until the rice is shaped as a thin circle, 1/2 inch thick or a little thicker (otherwise the final hamburger will get really thick). After forming the rice buns, open up the plastic wrap so that the heat won’t make moisture condense on the buns and set aside.
Repeat to form a total of 4 rice patties (2 tops and 2 bottoms).
The rice buns can be prepared several hours beforehand. To store, wrap the rice buns up in the plastic wrap. It’s preferable to wrap them after the rice has cooled so that moisture doesn’t condense on them, but not critical; if you’re in a hurry, it’s okay to wrap them when warm. The plastic wrap will help to prevent the rice from drying out. If you need to store them overnight, they should be refrigerated and wrapped in plastic wrap; they can be rewarmed by toasting (see below). They can also be frozen for longer storage–reheat using the toasting instructions below (no need to thaw first). Toast until they are hot throughout and lightly toasted on bottom; frozen rice buns will need to toast for slightly longer than unfrozen ones.
To toast the rice buns: Optionally, the rice patties can be toasted just before serving (Mos burger toasts their rice buns). Toasting the rice patties helps them hold together better and make them less sticky than cooked rice, and as a result the dish will be less messy (untoasted rice buns have a tendency to fall apart). You can choose whether to toast them lightly or until they are crispy. I prefer untoasted or lightly toasted rice buns, since the rice stays soft and moist and it melts into the other ingredients. If the rice buns are too crispy, I think it overwhelms the delicate nori and bonito flavors of the onigiri burger.
To toast: heat a well-seasoned cast iron pan on medium. If you are worried about sticking, then lightly brush either the bottom side of the rice buns or the pan with toasted sesame oil. It’s okay to use toasted (dark-colored) sesame oil for cooking on medium heat, but not high heat since it has low smoking point. Remove plastic wrap from rice patties and add the rice patties flat. Let sit undisturbed for at least 30 seconds; the rice patties may stick initially but as they cook they should detach from the pan. Cook, rotating occasionally to make sure that they cook evenly. I recommend cooking for a total of 3 minutes on one side only; the patties won’t brown in this amount of time and the rice won’t become very crispy–which is how I like it. However, you can also toast the rice buns until the bottoms become slightly browned if you want crispy rice (about 4 to 6 minutes, depending on temperature), and you can toast both sides of the bun if you prefer.
If using hamburger patties:
Cook or warm up hamburger patties. Preferably the hamburger patties should be thin; otherwise the entire rice burger will become very thick. Sprinkle a tiny bit of salt on top if you are using a hamburger patty.
If using leftover roasted pork shoulder:
Slice the roasted pork shoulder paper-thin or up to 1/8-inch thick (it’s okay if the slices are so thin that they only make it part of the way through the meat, though aim for some longer slices since this will hold together better). Thin slices are best, since you want them to break into pieces about as easily as the rice breaks apart.
Pan fry the slices (use a small amount of pork fat or oil to moisten the pan) it until the edges are golden and crispy. When assembling, sprinkle some surface salt on top of each layer; taste a small pieces and add more salt if needed. The salt should be noticeable; it should taste like nicely salty pork breakfast meat. Use a few slices (about 3 slices if they are 1/8 inch thick plus any small scraps) instead of the hamburger.
Pan Fry Eggs:
Pan fry two eggs, sunny side up, in lots of neutral-tasting oil which is heated to medium so that the sides bubble up and crisp. The edges may brown. If the oil splatters too much, turn down the heat slightly. Lightly salt the tops of the eggs when they are cooking. Set aside.
Assemble the Onigiri Burger:
- Pick one rice patty for the bottom. Leave the plastic wrap underneath this rice patty–since the rice is sticky, the onigiri burger should be served so that the plastic wrap can be used to hold the onigiri burger.
- Squeeze some kewpie mayonnaise over the bottom rice patty.
- Top with warmed hamburger patty or thinly sliced pork shoulder roast.
- Add fried sunny-side-up egg on top of the hamburger patty.
- Sprinkle toasted bonito flakes on top of the egg. Sprinkle salt on top very lightly; this is just to give it some surface salt.
- Remove the plastic wrap from the top patty. The bottom piece of wrap should be enough. Top the onigiri burger with rice patty.
Serve immediately, on top of a piece of plastic wrap so that the wrap can be used to hold the burger (otherwise it may be difficult to hold since the rice may stick to your fingers and fall apart).
Source: “Umami Dust”, recipe from Umami Burger via foodandwine.com
- 3 tablespoons bonito flakes
- 1/2 ounce crumbled dried kombu
- 1/2 ounce dried shitake mushrooms
Use a spice grinder to grind all ingredients into a fine powder.
This makes much more powder than is needed for these onigiri burgers, but the umami dust keeps for many months in a tightly covered container. It can be sprinkled on many items, include regular American burgers, which is how umami burger uses it.