Prep the vegetables. Peel and cube the sweet potatoes into even pieces so they cook at the same rate.
Dice the onion and peppers, and mince the garlic. Rinse and drain the black beans.
Heat the skillet. Set a large, heavy skillet (cast iron is ideal) over medium heat. Add 2 tablespoons of olive oil and let it warm until it shimmers.
Start the sweet potatoes. Add the sweet potatoes in an even layer.
Sprinkle with a pinch of salt. Cook undisturbed for 3 to 4 minutes to let the bottoms brown slightly.
Sauté and season. Stir the sweet potatoes and add the onion and peppers. Cook, stirring every couple of minutes, until the vegetables soften and the sweet potatoes are almost tender, about 8 to 10 minutes.
Add garlic and spices. Stir in the garlic, cumin, chili powder, smoked paprika, oregano, and coriander.
Cook for 30 to 60 seconds, just until fragrant. If the pan seems dry, add 1 teaspoon more oil.
Finish with beans and steam. Fold in the black beans and 2 tablespoons of water. Cover the skillet for 2 to 3 minutes to help the sweet potatoes finish cooking through.
Uncover and let excess moisture cook off.
Adjust and brighten. Season with 1/2 teaspoon salt and black pepper. Squeeze in the lime juice and toss. Taste and adjust salt, pepper, or lime as needed.
Top and serve. Sprinkle with cilantro.
Add your favorite toppings like eggs, avocado, queso, or salsa. Serve hot with extra lime wedges and hot sauce on the side.