Wash the peppers, remove the seeds and cut into rings and thick strips. Peel the onion and cut into thick rings. Wash and slice the tomato.
Season the vegetables with salt and pepper and brush with oil. Heat a grill- or serving pan. Dab the meat with absorbent kitchen paper and place in the hot pan with the vegetables. Turn the meat frequently.
Fry the vegetables for about 3 minutes each side. When the meat is cooked (juices run clear when tested with a skewer), drizzle with corn oil and season well with salt and pepper. Serve with a spicy barbecue sauce or lemon juice.