Prep the base. Dice the onion and mince the garlic. Lightly oil the bottom of the crockpot to prevent sticking.
Season the protein. Pat dry and rub with 1–2 teaspoons each of chili powder and cumin, plus 1 teaspoon smoked paprika, 1/2 teaspoon oregano, salt, and pepper.
Use less salt if your broth is not low-sodium.
Optional sear (adds flavor). In a hot skillet with a drizzle of olive oil, sear the protein for 1–2 minutes per side until browned. This step is optional but boosts depth.
Layer the ingredients. Add onions, garlic, peppers, tomatoes, and beans or lentils to the slow cooker. Place the protein on top.
Add liquids. Pour in the broth and tomato base (if using).
The liquid should come about halfway up the protein. Stir gently around the sides.
Cook low and slow. Set to Low for 6–8 hours or High for 3–4 hours. Chicken and turkey are done when they shred easily and reach 165°F.
Beef and pork should be fork-tender. Lentils should be soft but not mushy.
Finish with greens and acid. In the last 20–30 minutes, stir in spinach or kale. Add 1–2 tablespoons lime juice or vinegar to brighten the flavors.
Shred or slice. Remove protein and shred with two forks, or slice against the grain.
Return to the pot and stir to coat.
Taste and adjust. Add salt, pepper, or a splash of hot sauce. If too thick, add a bit more broth. If too thin, remove the lid and cook on High for 15–20 minutes.
Serve. Spoon over brown rice or quinoa, tuck into tortillas, or serve in bowls with Greek yogurt, cilantro, and avocado.