Tuna Sushi Stacks

Name: Tuna Sushi Stacks
Prep time: 20 min
Total time: 20 min
Cuisine: Asian, Japanese
Ingredients: 1/2 cup uncooked white rice (see note 1); 2 tablespoons rice vinegar; 1 large ripe mango (diced (1-1/4 cup)); 1/2 cup diced English cucumber; 1/4 cup diced red onion (1/4 of an onion); 1 large ripe avocado (see note 2); 2 large lemons (divided); 5 ounces olive oil packed tuna (well-drained); 1/2 cup mayo (divided); Cooking spray; 3 to 6 teaspoons reduced-sodium soy sauce; Salt and pepper; Sesame seeds (optional, I use black); 1-1/2 teaspoons Sriracha