In a large pot, heat a splash of oil over medium heat. Add the diced onion and bell pepper, cooking until softened, about 5 minutes.
Add minced garlic to the pot and cook for an additional 1-2 minutes until fragrant.
Increase the heat slightly and add the ground turkey or beef, breaking it apart with a spatula. Cook until browned and cooked through, about 5-7 minutes. Drain any excess fat if necessary.
Stir in the diced tomatoes (with and without chilies), beef or chicken broth, black soybeans, taco seasoning, and cumin. Bring to a simmer.
Once simmering, reduce the heat to low and let the soup cook for about 15-20 minutes, allowing the flavors to meld together. Stir occasionally. If desired, add frozen corn during the last 5 minutes of cooking.
Season the soup with salt and pepper to taste. Adjust the taco seasoning if you prefer a spicier flavor.
Serve hot in bowls, topped with shredded cheddar cheese, diced avocado, fresh cilantro, and sliced jalapeños if using.
Notes
Serve the taco soup in colorful bowls, sprinkle with extra cilantro, and add lime wedges on the side for a refreshing squeeze.