Heat oil in a large nonstick skillet over medium heat. Add onion, garlic, and buffalo; cook 5 minutes or until buffalo is done, stirring to crumble. Add tomato paste and next 4 ingredients (through pepper); stir well to combine. Stir in 2 cups water; bring to a boil. Reduce heat, and simmer 20 minutes or until thick.
Warm tortillas according to package directions. Spoon about 1/4 cup meat mixture onto each tortilla; top each tortilla with 2 tablespoons chopped tomato, 2 tablespoons lettuce, 1 tablespoon cheese, 1 1/2 teaspoons olives, and 1 1/2 teaspoons sour cream. Fold in half.