1. Combine first 6 ingredients; set aside.
2. Clip a fry thermometer to the side of a large, heavy saucepan. Add oil to pan; heat over medium-high heat until thermometer registers 375°. Reduce heat to medium, maintaining oil temperature.
3. Weigh or lightly spoon flour into dry measuring cups; level with a knife. Combine flour, beer, black pepper, 1 teaspoon salt, and garlic powder, stirring with a whisk. Add fish to batter, tossing gently to coat. Remove fish from batter. Carefully add 4 or 5 fish pieces to hot oil; cook 4 to 5 minutes or until golden brown and done, turning occasionally (maintain oil temperature at 375° throughout cooking process). Drain fish on paper towels. Repeat procedure in batches with remaining fish.
4. Heat tortillas according to package directions. Divide fish evenly among tortillas; spoon about 2 tablespoons salsa into each tortilla.