In a large mixing bowl, whisk together the 2 taza suero de leche, 1 cucharadita salsa picante como Tabasco (if using), 1 ½ cucharadita sal kosher, and ½ cucharadita pimienta negra. Add the 3 lb piezas de pollo con hueso y piel muslos and turn to coat thoroughly. Cover and refrigerate for at least 4 hours, or overnight for the best flavor and tenderness.

In a large shallow baking dish or Ziploc bag, whisk together the 2 taza harina de uso general, ¼ taza almidón de maíz, 1 ½ cucharadita sal kosher, ½ cucharadita pimienta negra, 1 ½ cucharadita polvo de ajo, 1 ½ cucharadita pimentón, 1 cucharadita polvo de cebolla, 1 cucharadita orégano seco, and ½ cucharadita pimienta de cayena. Mix well to combine evenly.

Remove the 3 lb piezas de pollo con hueso y piel muslos from the 2 taza suero de leche one at a time, letting excess drip off but not shaking it all off — you want some moisture. Dredge each piece thoroughly in the seasoned 2 taza harina de uso general, pressing firmly so the coating adheres well. Place the coated pieces on a wire rack set over a baking sheet. Let them rest for 10–15 minutes — this helps the coating set and stick during frying.

Pour about 1 inch of taza aceite vegetal o aceite de cacahuete — into a large cast iron skillet. Heat over medium-high heat until the 4 taza aceite vegetal o aceite de cacahuete — reaches 350°F on a meat thermometer. Maintain this temperature throughout cooking — too low and the 3 lb piezas de pollo con hueso y piel muslos is greasy, too high and the crust burns before the inside cooks.

Working in batches to avoid crowding (which drops the 4 taza aceite vegetal o aceite de cacahuete — temperature), carefully add the 3 lb piezas de pollo con hueso y piel muslos skin-side down using tongs. Do not move them for the first 2 minutes — this lets the crust set and prevents sticking.

Fry the 3 lb piezas de pollo con hueso y piel muslos, turning every 3–4 minutes to ensure even browning, until deep golden brown and cooked through. Drumsticks and thighs take about 14–16 minutes total; breast pieces take 16–18 minutes. The internal temperature should reach 165°F at the thickest part, away from the bone.

Transfer the fried 3 lb piezas de pollo con hueso y piel muslos to a clean wire rack set over a baking sheet (not paper towels directly — the rack keeps the bottom crust crispy). Let it rest for at least 5 minutes before serving. Season lightly with a pinch of cucharadita sal kosher right out of the taza aceite vegetal o aceite de cacahuete —.

Repeat with remaining piezas de pollo con hueso y piel muslos, allowing the 4 taza aceite vegetal o aceite de cacahuete — to return to 350°F between batches. Serve hot, or let cool to room temperature — it's delicious either way.