Chicken Teriyaki Sushi Bowl

Name: Chicken Teriyaki Sushi Bowl
Ingredients: 1½ cups long-grain brown rice, rinsed; 1 tablespoon seasoned rice vinegar; ½ teaspoon sea salt; ½ teaspoon garlic powder; 1 full-size sheet of sushi nori, minced; 1½ pounds boneless, skinless chicken breast, cut into 1-inch pieces; 1 (15-21-ounce) bottle teriyaki sauce, we like Soy Vay or Kona Coast brand; ⅓ cup mayonnaise; 1 tablespoon sriracha, plus more for serving; 2 teaspoons seasoned rice vinegar; 1 English cucumber, sliced; 1 large avocado, pitted, peeled, and diced; 2 full-size sheets sushi nori, cut into triangles; sesame seeds, (optional)