Preparation, Storage and Freezing Tips for Hamburger Casserole with Rice: Prep ahead: You can assemble this casserole in advance and keep it covered in the refrigerator for up to 24 hours … I hope you enjoy making this burger! Vegetable-based burgers like this one tend to replace the tang of beef with a heavy dose of umami. It’s made by pan-frying packed rice shaped into a bun and adding a burger paddy or any topping you like. In this recipe… Add beef and onions and sauté, stirring frequently, until meat is browned and cooked through, about 5-7minutes. Heat oil in a large skillet over medium-high heat. The rice burger was created in 1987 by the Japanese fast-food chain MOS Burger. To make the rice into a patty shape all you need to do is press the rice down into a small cake tin or make your own form by following the same guide that’s in the Extra Thick and Fluffy Pancakes recipe. The secret to get the rice to stick together is to make a 1/3 of the rice using sticky glutenous rice, the type we use to make mochi.