Cook the rice in 2 cups of water according to package directions in a medium saucepan or rice cooker.
Add the soy curls to a large mixing bowl. Pour the vegetable broth and soy sauce over top, ensuring that all soy curls are submerged. Set this aside to soak for 10 minutes.
Preheat the oven to 400°F (200°C).
When the rice has finished cooking, stir in the rice vinegar, sesame oil, and salt until evenly distributed. Then, transfer the rice to a 13x9 baking dish and use a spoon to smooth it out into an even layer. Once even, sprinkle the rice layer evenly with rice seasoning.
Strain the soy curls, gently squeezing them to remove excess moisture. Transfer the curls back into the mixing bowl. If desired, pull some of the larger soy curl pieces into thinner shreds using your fingers or two forks.
To the bowl of soy curls, add the mayonnaise, sriracha, sugar, and rice vinegar. Use a large spoon or spatula to mix the ingredients until the soy curls are evenly coated. Transfer the soy curls to the baking dish and spread them evenly over the rice layer. Evenly sprinkle with rice seasoning.
Bake at 400°F (200°C) for 20 minutes.
While the casserole bakes, slice the toppings. Drizzle some rice vinegar onto the avocado to keep it from browning.
Once baked, arrange toppings as desired. Serve with seaweed snack on the side for scooping sushi bake into before eating.
Store leftover sushi bake in the fridge in an airtight container for 3-5 days.