Season the chicken with 1 teaspoon salt and 1/2 teaspoon pepper. In a large heavy pot, heat the oil over medium high heat until hot. Sear the chicken, turning once, until browned, about 6 minutes. Transfer the chicken to a plate. Add the sausage to the pan and brown, turning once, 4 to 6 minutes. Transfer the sausage to the plate with the chicken. Stir the bacon fat into the pan and whisk in the flour. Reduce the heat to medium low and cook the flour, stirring frequently until it is several shades darker (about the color of natural peanut butter) an fragrant, about 20 minutes.