First, place eggplant in a colander over the sink and sprinkle salt generously all over, tossing and making sure all the eggplant is coated with salt. Allow to sit for 30 minutes.
After about 30 minutes, the eggplant should have released water. Rinse the salt off and lay the eggplant on a paper-towel lined baking sheet. Use other paper towels to press down, releasing additional water until it is dry.
Next, in a large skillet on medium heat, saute onion and serrano until cooked down and tender. Add garlic and cook for another 1-2 minutes until caramelized. Add cubed eggplant and cook for about 15 minutes until eggplant softens and breaks down.
Once eggplant is tender enough for your liking, season with salt and pepper add tomato paste and paprika. Mix well and continue to cook on low until eggplant is very soft and tender.
In a small bowl, mix together the glaze and set aside.
Lay 2 sheets of phyllo dough (or yufka) on a flat, clean surface. Use a pastry brush to brush dough with glaze mixture. Then use a table spoon to spoon eggplant towards the bottom of the pastry. Roll dough up, tucking in the sides like a burrito and lay in an oiled baking sheet, seam side down.
Finish with the rest of the mixture and brush glaze on the top of the borek. Sprinkle with sesame seeds.
Bake borek at 350 degree F oven for 25 minutes or until borek is golden brown. When done, allow to cool for 10 minutes before serving.