This recipe takes two days. On the first day, prepare the meat and marinate. On the second day, prepare the veggies and cook. Place meat in a bowl. In a small bowl, combine black pepper, garlic and oregano and sprinkle mixture over meat. Mix well to coat. In a blender, combine lemon juice and olive oil and blend. Pour over meat, cover and refrigerate overnight. The next day, brush onions and green pepper with olive oil and sprinkle with salt and pepper to taste. Thread meat and veggies, alternating, on to skewers. Barbecue on grill, being careful not to overcook. Use remaining marinate to bush on while cooking. Before serving, sprinkle with salt and fresh lemon juice.