In a large frying pan over medium heat, cook the ground beef, stirring and constantly breaking apart the beef.
When the meat is mostly cooked through, add the onions and bell peppers and continue cooking, stirring constantly until vegetables are soft and meat is cooked through.
Add garlic and cook for another minute. Add the water, tomato paste, and seasonings. stir to combine and reduce heat to low and simmer for about 5 minutes.
Pile on top of tortillas or taco shells and garnish with lettuce, sour cream, avocado, and cilantro.
