Heat oil in a large skillet over medium heat. Cook onion for 3 minutes.
Add sweet potato, pepper, spices, and water. Cover and simmer for 12–18 minutes, stirring occasionally. Add water in small amounts if the pan dries out.
When the potato is fork-tender, fold in beans. Cook uncovered for 3–5 minutes until hot.
Finish with lime and season to taste. Serve as a bowl or with tortillas.
Storage: Refrigerate perishables promptly in shallow containers. Use refrigerated leftovers within 3–4 days or freeze earlier. Reheat cooked leftovers to 165°F; keep cold meals chilled during transport. Follow ingredient labels if they require a shorter storage time.