Brown 1 ½ pounds lean ground beef in a skillet over medium-high heat, breaking the beef up with your spoon as you go along. Once the meat has browned, drain most of the fat (I like to leave a bit in for flavor), and add it to your slow cooker.
Add ½ medium onion chopped, 1 (12-ounce) can corn, 1 (14-ounce) can black beans, 1 (14-ounce) can red kidney beans, 1 (14-ounce) can fire-roasted diced tomatoes, 1 (4-ounce) can diced green chilis, 2 cups beef broth, 2 cups water, ¼ teaspoon dried oregano, ½ teaspoon garlic powder, ½ teaspoon onion powder, ½ teaspoon smoked paprika, ½ teaspoon chili powder, and ½ teaspoon cayenne pepper, to your Crockpot and give it a good stir.
Close the lid and cook on low for 6-8 hours or high for 3-4 hours.
Prior to serving, prepare your desired toppings. Give the soup a taste and season with salt and pepper if needed. Top the soup to taste and enjoy!
Notes
Anything from 1-2 pounds of ground beef will work.
If you're sensitive to salt, use low-sodium beef broth.
You can use regular diced tomatoes, but fire-roasted ones have more flavor.
If you don't want the soup to be spicy, leave out the cayenne pepper.