Heat a large pot over medium heat and add a splash of oil. Dice the onion and sauté until it turns golden and fragrant, about 5 minutes, stirring regularly.
Add the minced garlic and chopped bell pepper to the pot. Cook for another 2-3 minutes until the peppers soften and release their aroma.
If using ground meat, add it now and cook until browned, breaking it apart with a spoon, about 5-7 minutes. Drain excess fat if necessary.
Stir in the chili powder, cumin, salt, and pepper, cooking for 1 minute to toast the spices and deepen their aroma.
Add the drained black beans and diced tomatoes, including their juices, to the pot. Stir well to combine all ingredients evenly.
Bring the mixture to a gentle simmer, then reduce the heat to low. Cover the pot and let it cook for 20-25 minutes, stirring occasionally, until the beans burst and the flavors meld.
Taste the chili and adjust the seasoning with more salt, pepper, or spices as desired. If it becomes too thick, stir in a splash of water or broth to loosen it up.
Once the chili is thickened and the beans are soft with a squishy pop, turn off the heat and ladle the hot chili into bowls.
Top with your favorite toppings like sour cream, shredded cheese, or chopped cilantro for added flavor and creaminess.
Enjoy the rich, smoky, and hearty bean chili with a side of crusty bread or tortilla chips.