Combine the tomato sauce, paprika, oregano and cumin and marinate the shrimp in the mixture for at least two hours, covered and refrigerated.

Make the taco shells by placing the tortillas on a piece of baking parchment and draping them over one or two bars of the oven rack. Bake on medium heat until crispy.

Cook the shrimp on the grill, under the broiler or in a sauté pan. Discard any remaining marinade.

Divide the lettuce between the taco shells and add the cooked shrimp on top.