In a skillet, brown the ground beef until cooked. Drain grease and place ground beef in slow cooker.
Chop onion & green bell pepper and add to slow cooker.
Add diced tomatoes, tomato sauce, tomato paste, red kidney beans, chicken stock/water, and taco seasoning. Stir to combine.
Cook on low for 6 to 7 hours or high for 3 to 4 hours.
Serve with desired toppings such as shredded cheddar cheese and sour cream.