Cut the salmon fillet into bite-sized pieces.
Season the salmon with salt and pepper.
Heat olive oil in a pan and preheat.
Grill the salmon over medium heat until golden brown on each side.
Place the rice in a bowl and top with the grilled salmon.
Make a sauce with soy sauce, sugar, and mirin, and bring to a boil.
Pour the sauce over the rice and salmon.
Serve with avocado, thinly sliced onion, and sesame seeds.