To make the salsa verde: Heat a large cast-iron skillet or ceramic pan over high heat. When hot, add jalapeños, tomatillos, and onion and cook until blistered, turning often to evenly char the vegetables.
Transfer the vegetables to a blender, add cilantro and 1 cup water, and blend until chunky. If the salsa is too thick for your liking, add a little more water. Season to taste with salt.
To make the pico de gallo: Gently fold tomatoes, onion, chiles, and cilantro together in a large nonreactive bowl (stainless steel or plastic). Squeeze lime juice over the salsa, season with salt to taste, and stir gently until combined.
To make the tacos: Cut fish into rectangular strips about 5 inches long by 1 inch thick. To make the brine, put 1 quart water in a large container or nonreactive bowl and stir in 1 cup salt, cloves, and garlic powder. Add fish to the brine (there should be enough to cover) and refrigerate for about 2 hours.
When it's almost time to fry the fish, combine flour, 1 teaspoon salt, oregano, and baking powder in a large mixing bowl. Fold in mustard and mayonnaise. You should have a smooth, homogenous batter about the consistency of a light pancake batter so that it evenly coats the fish fillets. Add water if the batter is too thick.
Lay your condiments out before cooking the fish: salsa verde, pico de gallo, crema, shredded cabbage, lime wedges, and corn tortillas for your guests to assemble their own tacos, Baja style. If you want to really spice things up, make a variety of salsas and maybe some shredded cabbage pickled in lime for contrast.
Preheat the oven to 250˚F and line a baking sheet with paper towels. Remove fish from the brine and pat dry with paper towels. Heat a large Dutch oven or other heavy-bottomed pot over medium-high heat and add enough lard so fat melts to a height of roughly 2 inches. When the fat reaches 350˚F (check with a thermometer), use tongs to dip 2 or 3 fish fillets, one by one, into the batter so all sides are evenly coated. Lightly shake off excess batter. Place fillets carefully in the hot oil for 1 minute, then pierce the batter with the tongs and flip the fillets. Cook fish for 1 minute on the other side, then pierce the batter once more with the tongs and cook for another 1 to 2 minutes, depending on the thickness of the fish. Transfer the fried fillets to the paper-towel lined baking sheet to remove the excess oil. Put the baking sheet in the oven to keep fish warm while you fry the remaining pieces. Make sure the oil is bake to 350˚F before adding another batch of fish.
To serve, put a hot fish fillet into a room-temperature tortilla. Let everyone add his or her own condiments and finish with a squeeze of lime.