Mos burger is a Japanese fast food chain which offers Asian-style fast food. Several of their “hamburgers” use rice pressed into a bun shape instead of hamburger buns. I was recently able to try them at a baseball game I went to in Taiwan; Mos burger was one of the stands in the stadium. Unfortunately, I thought their fillings could have been better, but I was impressed by the idea of the rice bun enough 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 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.
Recipe: 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 cup 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:
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. Divide rice into 4 portions. Using a scale may help you to proportion the rice more evenly (or you could use a small bowl or measuring cup to estimate volume instead).
If think 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 if it has a “warm” setting or leave it in the rice cooker or pot with the lid on.
The rice buns can be formed either by using the plastic wrap or by wetting your hands to prevent the rice from sticking:
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.
To form each rice disk without using plastic wrap: 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.
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 so that they won’t dry out once the rice is cool (if you wrap them while they are hot, moisture will condense on them; this is acceptable but not preferable). 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 through out and lightly toasted on bottom; frozen rice buns will need to toast for slightly longer than unfrozen ones.
I prefer untoasted or lightly toasted rice buns, since this way 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 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). To toast: heat a well-seasoned cast iron pan on medium. 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 you need to use another type of pan for toasting the rice buns and are worried about sticking, then you can lightly brush the bottom side of the rice buns with sesame oil.
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 with the plastic wrap to use to hold the onigiri burger when eating.
- Squeeze some kewpie mayonnaise over the bottom rice patty.
- Top with warmed hamburger patty or thinly sliced pork shoulder roast. (If you forgot to salt the meat, then salt the top of the hamburger patty now, or gently salt between each layer of the pork slices.)
- 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. (If you forgot to salt the egg when cooking, then sprinkle a bit of extra salt on top of it now.)
- 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).
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.