Fried fish is the traditional filling of Baja tacos. They are simply garnished with shredded cabbage, pico de gallo, and sour cream.
Heat oil in a large cast-iron or heavy skillet until a deep-fry thermometer registers 375 degrees. Meanwhile, whisk together eggs, beer, 1/2 teaspoon salt, and 1/4 teaspoon black pepper in a medium bowl; set aside.
In a separate medium bowl, whisk together flour, remaining teaspoon salt and 1/4 teaspoon black pepper, and cayenne; add to egg mixture. Whisk until batter is well combined; let rest 15 minutes.
Dip fish strips one at a time into batter, letting excess drip off. Working in batches, drop carefully into hot oil; fry until fish is golden and crisp and cooked through, about 4 minutes. Remove with a slotted spoon; drain on paper towels. Serve immediately with warm corn tortillas, sour cream, salsa, and shredded cabbage.