Start by draining and rinsing canned black beans, or if using dried beans, soak them overnight in plenty of water. Drain and set aside.
Heat a large heavy-bottomed pot over medium heat, then add a tablespoon of olive oil. Once shimmering, add chopped onions and sauté until translucent and fragrant, about 5 minutes, until they start to turn golden.
Add minced garlic and cook for another 30 seconds until fragrant, stirring constantly to prevent burning.
Sprinkle in smoked paprika, toasted cumin (if using whole seeds, toast briefly and grind beforehand), and chili powder. Stir well and cook for about 30 seconds until the spices become fragrant and slightly darken in color.
Add the drained beans and diced tomatoes to the pot, stirring to coat everything evenly with the spices. Pour in the vegetable broth, then bring the mixture to a gentle boil.
Reduce the heat to low, partially cover the pot, and let the stew simmer gently for 1.5 to 2 hours if using dried beans, until the beans are tender and the broth has thickened to a velvety consistency. Stir occasionally to prevent sticking.
If using canned beans, simmer for 20-30 minutes to meld flavors and thicken the broth. Taste and adjust seasoning if needed, adding more spices or salt.
Once the beans are tender and the stew has thickened, remove from heat. Squeeze fresh lime juice into the pot, stirring to brighten the flavors.
Let the stew sit for a few minutes to allow flavors to meld, then serve hot, garnished with fresh herbs if desired. The stew should be thick, with soft beans and a smoky, vibrant broth.
