Step 1
Heat olive oil in a saucepan over medium-high heat. Add onion salt and lamb. Break up lamb into small crumbles. Cook stirring occasionally until most of the liquid evaporates about 8 minutes. Toss in garlic currants pine nuts cumin coriander cinnamon paprika black pepper cayenne and allspice. Cook and stir for 1 minute.
Step 2
Pour tomato sauce into the lamb mixture. Add water stir and reduce heat to medium. Cook until lamb mixture dries up and you can stir it without seeing liquid on the bottom of the pan 20 to 30 minutes. Turn off heat and let cool completely before using.
Step 3
In the meantime combine egg yogurt water and butter in a bowl. Whisk together thoroughly.
Step 4
Preheat the oven to 400 degrees F (200 degrees C). Butter a round baking pan or sheet pan.
Step 5
Place 2 sheets of phyllo on your work surface. Keep remaining sheets covered with a damp towel. Sprinkle some egg wash lightly on top and spread using a pastry brush. Layer on 2 more sheets one at a time brushing some more egg wash over each.
Step 6
Line 1/3 of the lamb filling along one wide edge of the phyllo. Roll pastry up starting from the filling side and place it against the edge of the pan. Brush more egg wash on top.
Step 7
Shape and fill 2 more rolls with remaining phyllo most of the egg wash and filling. Wrap rolls along and inside the first one filling the pan and brush with egg wash. Sprinkle sesame seeds on top.
Step 8
Bake in the preheated oven until browned and crisp 35 to 40 minutes. Let cool for 15 minutes.
Step 9
Combine yogurt mint lemon juice and garlic for the yogurt sauce. Mix in enough water to achieve desired consistency for dipping. Season with salt and cayenne. Cut borek into wedges and serve with yogurt sauce.