Dry the chicken cubes with paper towels and toss them with the flour, salt and pepper in a bowl. Heat the oil in a12-inch skillet until very hot but not smoking. Add the chicken cubes and cook in one layer turning occasionally, for about 3 1/2 minutes.
Meanwhile, combine the garlic and parsley in a small bowl. Add the butter and the parsley mixture to the skillet and sauté for 1 minute longer, shaking the skillet occasionally to coat the chicken. Divide among 4 plates, add a wedge of lemon to each plate and serve within 15 minutes.