"Quick, easy, and fun way to get acquainted with lamb! This recipe is best if domestic lamb is used, as it is much more mild and flavorful than imported lamb. The spices are the typical spices used in Mediterranean cooking of lamb. Makes 2-ounce patties."
Preheat an outdoor grill for medium-high heat and lightly oil the grate.
Mix garlic, cumin, coriander, allspice, salt, and pepper together in a bowl; add lamb and mix well. Form mixture into 2-ounce patties.
Grill patties on the preheated grill until cooked through, 2 to 3 minutes per side. An instant-read thermometer inserted into the center should read at least 160 degrees F (70 degrees C). Place rolls on the grill and heat until toasted, 1 to 2 minutes.
Layer spinach, tzatziki sauce, lamb patty, red onion, and feta cheese in each roll, creating a slider.