Secret sauce (Parmesan-oregano aïoli)
1 1/2 cups mayonnaise
1/2 cup finely grated Parmesan cheese
3 tbsp. finely chopped fresh oregano
2 tbsp. Dijon mustard
1 tbsp. horseradish
Kalamata biscuit buns
2 cups all-purpose flour
2 tbsp. brown sugar
2 tsp. baking powder
1/2 tsp. baking soda
1/2 tsp. salt
1/2 cup butter, cubed and frozen
1/2 cup drained and diced Kalamata olives
2/3 cup buttermilk, well chilled
1/2 cup crumbled blue cheese
2 lb. ground lamb
1 tsp. fine sea salt
1/2 tsp. black pepper
1/2 tsp. chipotle chili powder
To make sauce: Mix ingredients together in a small bowl. Refrigerate until ready to use.
To make biscuits: Preheat oven to 375 degrees. Add flour, brown sugar, baking powder, baking soda and salt to a food processor and pulse just to blend. Add frozen butter and pulse twice. Add olives and pulse just to incorporate. Separate egg. Add yolk to buttermilk and whisk to combine. Slowly pour into food processor while continuously pulsing, just until mixture becomes crumbly (do not overmix).
Transfer dough to a lightly floured board and gently flatten into an 8-inch circle. Sprinkle half of the dough with 1/4 cup cheese. Fold dough over and again flatten into an 8-inch circle. Place remaining cheese on top and fold dough over. Flatten dough to 1/2-inch thickness. Use a 2-inch round cutter to cut into 8 biscuits.
Place biscuits, evenly spaced, on a baking sheet or pizza stone. Whisk egg white until foamy and use a pastry brush to brush generously over the top of biscuits. Bake 18 minutes or until golden brown. Remove from oven. Let cool 10 minutes. Slice each biscuit in half and set aside.
To make sliders: Heat outdoor grill to 500 degrees. Form meat into 8 balls. Flatten each into a 3/4-inch-thick patty and make a small indentation in the middle, about 1/2 inch in diameter. In a small bowl, mix together salt, pepper and chipotle chili powder. Sprinkle seasoning on both side of patties. Cook on heated grill, with lid shut, for 5 minutes on each side or until internal temperature reaches 160 degrees. (Flip burgers only once and never press down with a spatula to check for doneness; you will lose all the juices.) Remove burgers from grill and cover with foil. Top the cut side of each biscuit with 2 tsp. sauce. Place a cooked burger on the bottom half of each biscuit and finish with the top half. You can use extra sauce for dipping or refrigerate for another use.
Serves 4 (2 sliders per person)