Preheat a generous amount of oil in a pan.

Meanwhile, make your tempura batter. Stir together the cornstarch, flour, salt, paprika, and seltzer in a bowl until smooth.

When the oil is hot, place a seaweed sheet on top of the tempura batter, lift up by the corners and gently place tempura-side-down into the oil. Working quickly, use tongs to shape into a taco shell and fry on each side until crisp. Remove to a wire rack and repeat with remaining seaweed snacks.

For serving, fill each shell with a bit of prepared sushi rice and toppings of your choice. Drizzle with your favorite sauce and enjoy immediately.