Place sushi mat, with slats running parallel, on work surface. Place 1 nori sheet, shiny side down, on mat lining up 1 long edge of nori sheet with edge of mat nearest you. Use moistened fingers to evenly press 1/4 of the cauliflower mixture onto nori sheet, leaving 1-3/4-inch border on long side of nori sheet farthest from you. Spread 1 Tbsp. mayonnaise mixture into horizontal row 1 inch from bottom of nori sheet. Place 1/4 each
of the shrimp, avocados and peppers over mayonnaise mixture.