In a large skillet, heat a splash of oil over medium-high heat. Add the 2 pounds of lean ground beef and cook for 4-5 minutes, breaking it apart with a spatula until browned. Stir in the diced onion, cooking until tender and translucent, about 4-5 minutes more.

Once the beef and onion mixture is sizzling, stir in the 4 minced garlic cloves, 2 tablespoons of chili powder, 2 teaspoons of cumin, 1 teaspoon of garlic powder, 1 teaspoon of oregano, 1.5 teaspoons of fine sea salt, and 0.5 teaspoons of black pepper. Let the mixture cook for another 30 seconds.

Carefully pour the fragrant beef mixture from the skillet into a 6-quart slow cooker. Scrape any tasty browned bits from the skillet into the cooker.

Add 1 can of drained and rinsed black beans, 1 can of drained and rinsed kidney beans, 30 ounces of diced tomatoes with juice, 10 ounces of diced tomatoes and green chiles with juice, and 15 ounces of tomato sauce to the slow cooker. Stir well to combine.

Cover the slow cooker and set it to cook on low for 6-8 hours or high for 3-4 hours.

When the cooking time is complete, lift the lid and gently stir the chili. Taste it, and if necessary, adjust the seasoning with more salt and chili powder.