Step 1: Prep and season the fillings: Slice the red pepper and onion into thin strips, and shred the chicken. Have the cheese, chicken, and veggies within reach — once the pan is hot everything moves in under a minute, so there is no time to hunt for things.
Step 2: Heat the skillet with fat: Warm a skillet over medium heat and swirl in the butter to coat. The pan is ready when you feel heat hovering above it — then food will not stick and browning stays even.
Step 3: Layer cheese and fillings: Lay a tortilla down, spread half a cup of cheese to cover it, then add the chicken and veggies, and finish with a little more cheese as "glue." Cheese above and below the filling is what keeps it together after folding.
Step 4: Fold and pan fry: Fold the tortilla into a half-moon and press gently. Fry 2–3 minutes per side until golden and the cheese melts. Add a dab more butter midway for an extra-crisp shell.
Step 5: Slice and plate: Rest off heat 1 minute so the cheese sets, then cut into wedges. Serve with salsa or sour cream, and eat while the cheese still stretches.
