Place all the marinade ingredients in a pan and bring to the boil over a medium heat; allow to reduce slightly. Add some water if the marinade becomes too thick. Pour the marinade into a shallow dish and add the steaks; leave to marinate for approx. 2–4 hours.
Remove the steaks from the marinade, wipe off some of the marinade – serve the rest later as a dip. Barbecue the steaks for approx. 6–7 minutes on each side.
Wash the vegetables and cut into medium-sized cubes. Arrange on the aluminium grill trays and crumble the feta over the top. Drizzle with olive oil and season generously.
First place the grill trays in the middle of the barbecue for a few minutes, then move to the side and prepare the steaks. The cheese should be slightly runny and the vegetables tender.