In a medium bowl, whisk together flour, salt, pepper, and beer until smooth to create the batter.
Heat 2-3 inches of vegetable oil in a heavy pot or deep skillet to 375°F.
While oil heats, combine cabbage, red onion, cilantro, cider vinegar, vegetable oil, and a pinch of salt in a large bowl. Toss well and set aside.
In a blender or food processor, combine mayonnaise, lime juice, chipotle chiles, and garlic. Blend until smooth.
Dip fish strips into batter, allowing excess to drip off, then carefully lower into hot oil.
Fry fish in batches for 3-4 minutes until golden brown and crispy. Transfer to paper towels to drain.
Warm tortillas in a dry skillet or directly over gas flame until pliable and lightly charred.
Assemble tacos by placing fried fish on tortillas, topping with cabbage slaw and chipotle sauce.
Serve immediately with lime wedges on the side.