Cut each shrimp into two or three pieces, Spritz a little lime over the shrimp to moisten- don't overdo it - and refrigerate.
Make the batter: Combine the flour and seasonings in a bowl and mix thoroughly with a whisk. Add the beer all at once, whishk until smooth, and set aside at room temperature for 30 minutes.
Pour the oil into a deep, wide pan to a depth of 2 inches and heat over medium-high heat to 365 degrees.
Check the batter; it should be a thick coating consistency. If it seems too thick, add beer, water, or milk, 1 teaspoons at a time, until the right consistency is achieved. It's better to be slightly too thick than too thin!
Pat the shrimp dry and add to the batter. Fish out a ew pieces at a time and fry until golden brown. Drain the shrimp on paper towels.
To prepare hold a tortilla in your hand and add a spoonful of avocado sauce (directions for sauce are in the following step). Add the shrimp, a squeeze of secret sauce (recipe follows), and a healthy shot of hot salsa. Top with lettuce, pico de gallo, and onion and cilantro. Squeeze lime over the whole thing.
Avocado Sauce: Place the avocado, salt, and lime juice ina blender or small food processor. Add 1 tablespoon water and pulse. Add more liquid as necessary to make a sauce the consistency of thick cream. Add the cilantro and pulse again just to blend. Taste for seasoning; it should be a little bland.
Mayonesa Secret Sauce: Place the mayonnaise in a bowl and use a fork to slowly stir in vinegar to taste. Add water to loosen to the consistency of thick cream.