In a small bowl, whisk together sour cream, mayonnaise, chipotle peppers, and lime juice to create the crema. Set aside.
In a medium bowl, combine shredded cabbage with a splash of lime juice and cilantro for the slaw.
In a large bowl, whisk together flour, cornstarch, baking powder, salt, and cayenne pepper.
Gradually whisk the cold beer into the dry ingredients until a smooth batter forms.
Heat vegetable oil in a deep skillet or pot to 375 degrees Fahrenheit (190 degrees Celsius).
Pat shrimp dry with paper towels, dip into the batter to coat thoroughly, and carefully drop into the hot oil.
Fry shrimp in batches for 2 to 3 minutes until golden brown and crispy, then drain on a wire rack or paper towels.
Warm the corn tortillas on a dry skillet over medium heat.
Assemble tacos by placing 3 shrimp on each tortilla, topping with cabbage slaw and a drizzle of chipotle crema.