In the bowl of a standing mixer, set with the paddle attachment, beat the egg whites at medium speed until stiff, but not dry, peaks form. Remove the bowl from the mixer.
In another bowl, combine the all-purpose flour with the salt and cumin and whisk in the Mexican beer. In 4 additions, gently fold the flour mixture into the egg whites, taking care not to deflate the egg whites.
Pour the oil into a heavy, wide skillet or casserole to a depth of ¼” and heat over medium heat for at least 5 minutes. Test the heat by dipping a wooden spoon or the tip of a piece of fish into the oil: it should bubble happily around whatever you introduce into it. Set a cooling rack on a baking sheet and cover the rack with paper towels. If you don’t have a cooling rack, just cover the baking sheet with paper towels.
While the oil is heating, you can season and flour the fish strips. Season them lightly with salt and pepper. Place flour on a plate, and gently press each fish strip into the flour, flip over and flour the other side. Tap off excess flour and place on the rack.
When the oil is hot, one by one, dip the floured fish strips into the batter and immediately, but gently, place into the hot oil. Add as many as you can without crowding the pan. Fry until crisp and lightly golden brown, which should take 2 to 3 minutes; then flip and fry on the other side, for another 2 to 3 minutes or until crisp and lightly golden.
Remove with tongs – the type with the heat-proof coating on the ends are best, if you want to avoid tearing the batter – or a slotted spoon and place on the paper towel-covered rack. Cover loosely with foil to keep warm. Serve on a flour tortilla with salsa macha and creamy slaw. Optional, pickled red onion and a jalapeño marinated in fresh squeezed lime juice and salt to taste.
Credit Pati Jinich