Preheat a barbecue or char-grill on high.
In a food processor, blend mint, oil, lemon zest and 2 tablespoons lemon juice until mint is finely chopped. Season with salt and pepper.
Cook on the barbecue for 5 minutes each side. Reduce heat to medium-low and cook, covered, for 10 minutes for medium, or until cooked to your liking.
Transfer to a plate and cover with foil. Set aside for 15 minutes to rest.