Toss chicken with flour so that it is lightly dusted. Put 2 tablespoons oil in a large skillet, preferably nonstick, and turn heat to high. When oil smokes, add chicken in one layer. Sprinkle with salt and pepper.

When chicken browns on one side, toss it and cook until just about done: smaller pieces will take 5 minutes total, larger pieces about 10. Remove to a plate. Turn off heat and let pan cool for a moment.

Add remaining oil to pan and turn heat to medium high. Add garlic and cayenne pepper and cook, stirring, about 2 minutes. Add ketchup and stir; cook until ketchup bubbles, then darkens slightly. Return chicken to pan and stir to coat with sauce. Taste and adjust seasoning, then serve.