In a medium bowl, whisk together the ½ cup flour, baking powder and ¼ teaspoon each salt and pepper. Add the egg white and beer, then whisk until the batter is smooth and frothy; it should have the consistency of pancake batter. Let rest at room temperature for 5 to 10 minutes.
Distribute the shrimp in an even layer on a large plate, sprinkle with the remaining 1 tablespoon flour and toss to coat.
In a nonstick 12-inch skillet over medium-high, heat the oil until shimmering. Using your hands, dip 1 or 2 shrimp into the batter until fully coated, allow excess to drip back into the bowl and place the shrimp in the skillet. Continue in this way until half of the shrimp have been coated and added to the pan. Cook until the shrimp are golden brown on the bottom, 2 to 3 minutes. Using a thin metal spatula, flip the shrimp and cook until the second sides are golden brown, about 2 minutes; adjust the heat as needed if the shrimp are browning too quickly. Transfer to a paper towel–lined plate. Batter and cook the remaining shrimp in the same way; if the batter becomes too thick, whisk in additional beer as needed to restore to the consistency of pancake batter.
Divide the shrimp evenly among the tortillas. Top as desired with the cabbage, cilantro, chipotle mayonnaise, pico de gallo and salsa. Serve with lime wedges.
