Cut the salmon and avocado into bite-sized pieces.
Thinly slice the cucumber, radish, and red onion.
Place the salmon, avocado, cucumber, radish, and red onion into a bowl.
Make sour soy sauce (soy sauce + vinegar + sugar) and pour it over the ingredients, then mix well.
Serve the ingredients over rice and top with seaweed, sesame seeds, wasabi, and other preferred toppings.