Turkish Tahini Sweet Rolls (Tahinli Ekmek)

First off, check the expiration date of the instant yeast package.
To make the dough: In a large bowl, mix together the flour, butter, olive oil, sugar, salt, instant yeast and vanilla.
Beat the eggs in a bowl, and gradually pour the milk while stirring. Add to the flour mixture.
Knead the dough thoroughly until it is of one texture. Cover with a kitchen towel and set aside for 1 hour allowing it to rise and double in size.
Meanwhile, mix together the tahini and sugar until well combined.
Divide the dough into 12 equal balls. Working with one ball at a time.
Roll each ball, using a rolling pin, on a floured surface into a circle with 20 cm/8 inches in diameter.
Spread a tablespoon of the tahini mixture almost covering the circle, leaving 1 cm boarder around the edges.
Roll up each to form a log. Roll it back and forth a bit until it is about 30 cm/12 inches.
Use your hands to shape it into a tight spiral. Lightly flatten each with your hands.
Transfer the rolls to a parchment lined oven sheet, leaving some space between one another (you may probably need to use two oven sheets). Set aside the rolls for another 30 minutes, for a second fermentation.
For the egg wash: In a small bowl combine together the egg and vinegar and brush the tops of each spiral with the egg.
Lightly sprinkle with sesame seeds.
Preheat the oven to 200°C/ 400°F. Bake for 20 minutes or until golden and cooked through. Serve warm! How delicious!