In a bowl, whisk beer, flour, and salt until well blended.
Rinse fish and pat dry; cut crosswise into 1-inch-wide strips.
Pour about 1 inch of oil into a 10- to 12-inch dutch oven over medium-high heat; bring oil to 360°. With a fork, dip each piece of fish into beer batter; lift out and let drain briefly. Slide fish into oil, a few pieces at a time, and cook until golden (adjust heat to maintain 360°), turning if necessary to brown on all sides, 2 to 4 minutes per batch. With a slotted spoon, transfer to a paper towel-lined baking sheet. Keep warm in a 200° oven while you fry remaining fish.
To assemble each taco, stack two tortillas and top with a couple of pieces of fish, then a spoonful of cabbage and cilantro slaw. Serve with the chipotle tartar sauce to add to taste and lime wedges to squeeze over the top.
*To heat tortillas, wrap in foil and place in a steamer basket over boiling water, or microwave in a kitchen towel about 1 minute. Or, for a smoky char, toast directly on stovetop burner, turning often.