Prep your produce. Peel and dice the sweet potatoes into even cubes so they cook at the same rate.
Dice the onion and bell pepper, and mince the garlic. Rinse and drain the black beans.
Heat the pan. Warm a large skillet over medium heat. Add olive oil and swirl to coat.
Sauté the aromatics. Add the onion and bell pepper with a pinch of salt.
Cook for 3–4 minutes, stirring occasionally, until they begin to soften and turn fragrant.
Add sweet potatoes. Stir in the sweet potatoes and another drizzle of oil if the pan looks dry. Cook for 6–8 minutes, stirring every couple of minutes, until the edges start to brown.
Season. Sprinkle in cumin, chili powder, smoked paprika, cinnamon, and red pepper flakes if using. Stir to coat the vegetables so the spices bloom and become aromatic, about 30 seconds.
Steam to soften. Pour in the vegetable broth or water and cover the skillet.
Reduce heat to medium-low and cook for 5–7 minutes, or until the sweet potatoes are tender when pierced with a fork.
Add garlic and beans. Remove the lid, stir in the garlic and black beans, and cook for 2–3 minutes to warm the beans through. Adjust heat as needed to prevent sticking.
Finish with brightness. Squeeze in the juice of half a lime and fold in chopped cilantro. Taste and season with salt and black pepper.
Add more lime if you like extra zing.
Serve your way. Spoon into bowls as a main dish, or tuck into tortillas. Top with avocado, a dollop of sour cream or Greek yogurt, and a sprinkle of cheese if you like.