Season chicken breast with salt and pepper. Dust with flour, shake off excess. Heat half butter in skilet until melted. Saute chicken until well brown. Set aside. Add rest of butter to pan. Saute onions and garlic until limp. Sprinkle with cumin and chile powder. Add broth. Reduce broth by half. Puree avocado with salsa. Add to reduced broth. Place chicken in pan. Gently heat. Pour sauce around chicken to warm it. Serve.