Warm the pot. Set a large soup pot or Dutch oven over medium heat. Add olive oil if needed.
Brown the beef. Add the ground beef.
Cook, breaking it up with a spoon, until no longer pink, about 5–7 minutes. If there’s excess fat, spoon it off.
Sauté the aromatics. Add the onion and bell pepper. Cook until softened, 4–5 minutes.
Stir in garlic and cook 30 seconds, until fragrant.
Build the base. Stir in tomato paste and cook 1 minute to caramelize slightly. Sprinkle in all the taco seasoning. Toss to coat the beef and veggies.
Add the bulk. Pour in the broth.
Add diced tomatoes, black beans, pinto or kidney beans, and corn. Stir well, scraping up any browned bits from the bottom.
Simmer. Bring to a gentle boil, then reduce to a simmer. Cook uncovered for 12–15 minutes, stirring occasionally, until the flavors meld and the soup slightly thickens.
Finish and season. Stir in lime juice.
Taste and season with additional salt and pepper as needed. If you want more heat, add red pepper flakes or hot sauce.
Serve. Ladle into bowls and add your favorite toppings. For a lighter bowl, choose cilantro, jalapeños, and a squeeze of lime.
For extra comfort, add a small handful of cheese and a few crushed tortilla chips.