a relatively cheap NON-VEGE way to add protein to this base is pork butt/shoulder (same thing) cooked slow all day, either slow cooker or oven at 250F. Its a cheaper cut of meat and one of them is enough to add protein to like 6 servings or rice+beans. Also, bone-in skin-on chicken thighs are great and less expensive- if you render some of the chicken fat out in your cooking vessel before cooking the rice and beans it is a big flavor boost.