1. Pre-heat oven to 200*
2. In a saucepan, melt the butter over medium heat. Add the onion and salt, mix and cover. Cook for about 20 -30 minutes, stirring through to ensure that the onion does not stick to the pan.
3. Combine yoghurt, lemon & basil
4. Divide Parmesan into four lumped portions and bake for 3-4 mins watching closely.
5. Mix together lamb mince, minced garlic, paprika, cayenne pepper, fresh mint, oregano, cumin, Lamb herbs, salt & pepper. Bring together lightly, making sure not to overwork.
6. Form mince into 4 patty portions (reserving a small ball) . Make a small divot in the centre of each and fill with feta cheese. Cover with a small amount of remaining mince to completely enclose feta.
7. Toast the brioche buns.
8. BBQ or grill patties for 4-5 minutes each side.
9. Assemble burgers. Spread cranberry relish on the bottom bun, place lamb and Top with rocket and drizzle yoghurt sauce on top. Finish with parmesan crisp and burger bun.