Tenderloin is the best meat for barbecuing; delicious, succulent and easy to work with. The grilled lemons add a natural sweetness.
Rub the meat with the spice mixture. Peel the cucumber, slice it in half lengthwise and remove the seeds. Coarsely grate the cucumber and squeeze out the liquid. Combine with the yoghurt, herbs and cumin. Barbecue the steaks on high heat, turning them over often so they don’t burn. Cover with the Castello Blue Cheese Slices and let it melt. Slice the lemons in half and grill them with the flesh side down. Peel and slice the onion. Slice the tomato. Rinse and chop the lettuce. Toast the buns. Press juice from the grilled lemons over the steaks then top each bun with steak, lettuce, onion and tomato. Serve with the tzatziki.