Cut the salmon into small pieces and place it in a medium bowl. Add the spicy mayonnaise and teriyaki sauce and stir until well combined. Cover the bowl and place it in the refrigerator.
Cut the nori sheets into 12 large squares, approximately 3x3 inches (7.5x7.5cm) each. Set aside any extra pieces.
Spoon about 2 tablespoons of the cooked sushi rice onto each sheet of nori, leaving a ¼ inch border around the edges.
Place each nori sheet on top of a muffin tin compartment and use a spoon or your hands to press down the sheet to form a cup shape. Then, spoon the salmon mixture into each rice-lined nori cup.
Place the muffin tray into the preheated oven and bake for 15-20 minutes.
Remove the cups from the oven and allow them to cool in the muffin tins for about 15 minutes to help them retain their shape.
Carefully remove each cup from the tin by lifting the corners of the seaweed.
Garnish with a drizzle of additional spicy mayonnaise, sesame seeds and green onion before serving.