If using leftover rice and salmon, combine them in a microwave-safe bowl and add ice. Cover with parchment paper and microwave for 1-1½ minutes. Skip this step if using freshly cooked rice and salmon.
Remove any remaining ice. Add tsuyu and a drizzle of both mayonnaise and sriracha.
Use a fork to mash everything together.
Top with sliced avocado and green onion and serve with nori.