About 30 minutes before grilling, take the ground lamb out of the fridge.
Mix together the herbs, paprika, cayenne pepper, cumin, raisins and garlic and pour over the lamb. (Do NOT add any salt at this point)
Gently work together using your hands until the herbs are evenly distributed through the meat, being careful not to overmix.
Divide the mixture into 6 equal portions and form into patties.
With two fingers, gently press into the middle of each burger, this will help reduce shrinkage.
Preheat a grill over medium high heat for 5-10 minutes.
Wait until you are just about to grill to generously sprinkle the patties with salt and pepper to taste.
Grill over medium high heat with the lid closed for 5 minutes.
Flip burgers to the other side and continue to grill for another 5 minutes for medium/medium rare.
When there is about 1-2 minutes of grill time remaining, top your burgers with a few slices of feta cheese and grill your brioche buns (if desired).
After the 5 minutes, promptly remove your burgers from the grill to a baking sheet lined with tin foil. Allow meat to rest for at least 5 minutes before assembling.