Sour cream, pickled jalapeños, chopped onion, guacamole and hot sauce, for
In a medium bowl, using your hands, mix the masa harina with the water and 1/2 teaspoon salt until a soft dough forms. Cover the bowl with plastic wrap and let the dough stand for 30 minutes.
In a medium bowl, toss the chicken with the cheddar, queso fresco and chorizo. Season with salt and cayenne.
Divide the dough into 8 pieces and roll each piece into a ball. Working with 1 ball at a time and keeping the rest covered, press the dough in the palm of your hand to form a cup with walls about 3/8 inch thick. Spoon 2 tablespoons of the chicken filling into the cup and pinch to seal. Pat the filled dough into a flat 4-inch patty; pinch to seal any cracks. Set the pupusa on a baking sheet and cover with plastic wrap. Repeat with the remaining balls of dough and filling.
In a large, nonstick skillet, heat 1/2 cup of the oil until shimmering. Add 4 pupusas and cook over high heat, turning once or twice, until golden and crisp outside and heated through, about 5 minutes. Repeat with the remaining pupusas, adding more oil to the skillet as needed. Serve the pupusas with sour cream, pickled jalapeños, chopped onion, guacamole and hot sauce.
The uncooked pupusas can be stacked between sheets of wax paper, wrapped in plastic and refrigerated overnight.
Masa harina can be found in supermarkets. A popular brand is Maseca.