Place tomatoes and onions on a baking tray, sprinkle with oregano, season and drizzle with the olive oil. Bake for 30 minutes until the onions are soft and the tomatoes are tinged slightly brown around the outside.
While the tomatoes are cooking, preheat the barbecue, and brush the steaks with olive oil.
Cook for 3-4 minutes on each side turning once only.
Remove from the heat and allow to rest for 5 minutes before serving.
Serve the steak over the tomato and onion with an accompanying green salad of spinach leaves and avocado.
Note: Oregano is good source of antioxidants, believed to relieve indigestion and boost the immune system.