Combine salsa, half of the oil, cilantro, chili powder, garlic, cumin and salt in a large bowl. Add beef; cover and marinate in the refrigerator for at least 1 hour.
Heat remaining oil in a large skillet over medium-high heat. Add red and green bell peppers and onion; cook, stirring occasionally, for 5 to 6 minutes or until onions are slightly golden and peppers are tender. Add beef mixture; cook, stirring occasionally, for 7 to 8 minutes or until meat is no longer pink.
Serve in tortillas; top with sour cream.
Servings: 6