Heat the oil in a large skillet over high heat. Sear the steaks on both sides and set aside. In the same skillet over medium heat, saute the red bell pepper, green bell pepper, onion and garlic for 5 minutes, or to desired tenderness.
Sprinkle the steaks with the fajita seasoning and place them back in the skillet. Squeeze the lime juice over the steaks and bell peppers, reduce heat to low, cover and simmer for 30 minutes to 1 hour, turning steaks over occasionally. (Note: The longer it simmers, the more tender the meat gets.)