Scott Serpas serves this enticing sushi roll at his namesake restaurant Serpas in Atlanta, and created this recipe so that you can make it at home.
Preheat the oil in a heavy skillet to 350 degrees.
To make the tempura batter, mix together the flour, cornstarch, 1 teaspoon of salt, and baking powder. Slowly drizzle in ice water until you have a ribbony consistency, about 1 cup.
Dip each shrimp half into the tempura batter and shake off any excess. Fry in the oil for 1 minute, then remove from the oil and drain on a paper towel. When frying the shrimp, be careful not to overcrowd the pan so that temperature remains a constant 350 degrees throughout.
To make the spicy mayo, combine the mayonnaise, Sriracha, rice vinegar, and a pinch of salt to taste in a small bowl. Refrigerate until ready to use.
Place the rice papers in a bowl half full of warm water until completely soaked and then wipe off any excess water. Place the papers on a clean, dry surface. Place 1 ½ leaves of bibb lettuce ¾ the way down a sheet. Place a few slices of mango and avocado on top of the lettuce. Top with a couple of tuna slices and 3 shrimp halves. With your fingers placed on the top of the filling and your thumbs placed underneath the rice paper, fold the bottom lip of the rice paper onto the tuna roll. While pulling the filling, roll tightly. Roll until set. Slice the roll into 4-6 pieces and garnish with the spicy mayonnaise, sesame seeds, and scallions.