Cook the rice in advance and let it cool.
Cut the salmon, tuna, or other proteins into bite-sized pieces.
Slice vegetables like cucumber, avocado, and onion into easy-to-eat pieces.
Mix soy sauce, sesame oil, vinegar, and sugar to make the sauce.
Place the rice in a bowl and add the ingredients and sauce on top.
Sprinkle toppings like seaweed and sesame seeds.