Peel and cut the sweet potato into 3/4-inch cubes, dice the onion into 1/2-inch pieces, mince the garlic cloves, and squeeze the lime juice. Chop the cilantro and set aside. Drain and rinse the black beans. Having everything prepared before you start cooking ensures smooth execution and prevents burning of aromatics.

Heat 3 tablespoons of olive oil in a Dutch oven or large pot over medium-high heat. Add the diced onion and sweet potato cubes, stirring occasionally, and cook for about 4 minutes until the onion begins to soften and the sweet potato starts to caramelize at the edges. This initial sauté develops the foundation of flavor and allows the vegetables to release their natural sugars.

Add the minced garlic, chili powder, ground cumin, ground chipotle chile, and salt to the pot. Cook for about 30 seconds, stirring constantly, until fragrant. This brief cooking step, called blooming, activates the spices' essential oils and prevents them from tasting raw or bitter. I find that blooming spices in fat creates a much deeper, more authentic chili flavor than adding them later.

Pour in 2.5 cups of water or vegetable broth, stirring well to combine with the spice mixture. Bring to a simmer, then reduce the heat to medium-low, cover the pot, and simmer for 10-12 minutes until the sweet potato cubes are completely fork-tender. The covered simmer allows the sweet potato to cook through gently while the flavors meld together.

Stir in the drained and rinsed black beans, the canned diced tomatoes (with their juice), and the fresh lime juice from Step 1. Bring the mixture back to a gentle simmer and cook uncovered for about 5 minutes, stirring occasionally, until the chili thickens slightly and the flavors fully integrate. I like to add the lime juice here rather than at the very end because it has time to mellow into the sauce, creating better balance than a sharp citrus finish.

Remove the pot from heat and stir in the chopped cilantro. Taste and adjust seasoning as needed. Ladle into bowls and serve hot. Adding the cilantro off heat preserves its fresh, bright flavor and aroma rather than cooking it into a dull, bitter taste.