Gather the ingredients. Preheat oven to 400°F.
Begin with cooking the sushi rice. Rinse the rice in cold water, mix it up with your hands, and drain the water. Do this three times. You want the water to run clear after rinsing. See below for methods for how to cook sushi rice: Instant Pot Method: Combine the rice with 1.5 cups of water in the bowl of the Instant Pot. Cover and pressure cook on high for 5 minutes. All the pot to natural release for 10 minutes, and then quick release. When done, fluff with a fork. Stovetop Method: Combine the rice with 2 cups of water in a medium saucepan. Allow the rice to soak for 15 minutes before cooking. Turn the stove on to medium heat and let the rice come to a boil, then reduce heat to low. Cover the saucepan and simmer for about 20 minutes or until the rice has absorbed all the liquid. Remove from heat and let it sit covered for 10 minutes. Fluff with fork. When rice is finished cooking, add rice vinegar, sugar, and salt. Gently fold the rice to mix all the ingredients together. Set aside and allow to cool as you prepare the rest of the ingredients.
Next, chop the imitation crab into small pieces. Place in a medium bowl.
Chop the salmon into small chunks and add it into the same bowl.
Next, add the Kewpie mayonnaise, Sriracha, and the whites of the chopped green onion into the bowl. Gently stir to combine all the ingredients. Set aside.
Now it's time to layer the sushi bake. In an 8x8 dish, take all the sushi rice and spread it onto the bottom of the dish. You can make this easier by wetting your fingers before using them to spread an even layer of rice in the pan.
Next, sprinkle over the furikake so there's an even layer on top of the rice.
Lastly, evenly spread a layer of the salmon mixture over the rice. Pop the dish onto the middle rack of the oven at 400°F for 15 minutes, or until the salmon is fully cooked.
Remove the dish from the oven. Drizzle unagi sauce and additional Kewpie mayonnaise if desired. Then top with green onions and more furikake. Serve with roasted seaweed and/or optional toppings. Enjoy!