Cook the rice according to package directions. Mix with rice vinegar and let cool.

Make the mango salsa: combine diced mango, cucumber, red onion, and ½ tablespoon lemon juice.

Mash the avocado and season with salt and pepper.

Prepare the tuna mixture: stir together tuna, ¼ cup mayonnaise, and ½ tablespoon lemon juice.

Whisk the spicy mayo: mix remaining ¼ cup mayonnaise with sriracha.

Assemble: spray a 1‑cup measuring cup with cooking spray. Layer mango salsa, avocado, tuna, and rice. Flip onto a plate and drizzle with spicy mayo and soy sauce.