In a large skillet, heat over medium heat and add the lean ground beef, chopped white onion, and minced garlic. Cook for 8-10 minutes, stirring occasionally until the beef is browned and the onions are tender and translucent. Drain excess grease.

Carefully transfer the beef mixture into a greased slow cooker, scraping the skillet to capture all bits.

Add the undrained diced tomatoes, chili beans in sauce, and tomato sauce. Sprinkle in the chili powder, ground cumin, and desired salt and pepper. Stir until well-combined.

Cover and cook on low for 6 hours to allow flavors to deepen into a rich chili.

Ladle the chili into bowls and top with sour cream, grated cheese, sliced green onions, and Fritos.