In a large skillet over medium-high heat, cook lean ground beef until browned, about 8 to 10 minutes. Drain excess fat.

Add chopped white onion and diced green bell pepper to the skillet. Cook until softened for about 5 minutes.

Stir in chili powder, garlic powder, onion powder, salt, and black pepper; cook for an additional 5 minutes.

Transfer mixture to slow cooker; add diced tomatoes, tomato sauce, Rotel, salsa, chili beans, and black beans. Combine well.

Cover and cook on low for 6 to 8 hours or high for 5 to 6 hours.

Remove lid 30 minutes before serving to thicken chili; stir occasionally.

Ladle chili into bowls and top with garnishes like shredded cheese, sour cream, or chopped green onions.