1. Preheat oven to 190ºC.
2. In a large bowl, toss together onions, butter, balsamic vinegar and thyme, season with salt and pepper.
3. Place in a baking dish and cover with aluminum foil.
4. Bake for 40 minutes or until tender.
5. Remove foil and allow to cool a little.
6. When cool enough to handle, break apart the wedges into pieces. Keep mixture warm.
7. Grill steaks to desired doneness. Allow to sit for 5 minutes before slicing.
8. In large bowl, toss together the potatoes, dill, roasted onions, cos lettuce, oils and Castello® Double Crème White cheese pieces. Season with salt and pepper.
9. Cut each steak into bite-sized slices and arrange equally between 4 serving plates. Top steaks with salad and serve.