Combine oil, southwest spice, lime zest and garlic in a mixing bowl
Trim flank steaks and place in a bag with the marinade refrigerate at least six hours
Set the grill for direct cooking (medium-high)
Remove the flank from the bag and season with salt
Grill over direct heat for 3 minutes and turn over, continue to sear 3 minutes
Turn off middle burners to finish cooking using the indirect method
Season the peppers and onion with olive oil, salt and pepper
Grill over direct heat to lightly char the peppers and onion
Check meat, grill to desired temperature and remove from grill. Let rest before slicing
Remove the peppers and onion and cut into strips
Turn the grill down to medium-low and grill the flour tortillas over direct heat
Slice the flank against the grain and build the fajitas.
Yield: 6-8 portions