In a large pot, saute meat, onion and garlic in oil over medium heat until browned. Stir in cumin, chili powder, salt and pepper. Add tomatoes, breaking them up into small pieces as you add them. Add water and mix well. Simmer over low heat, uncovered, for 1-2 hours. Stir occasionally to prevent sticking and add more water if necessary. Makes 6-8 servings.