In a small bowl combine 1/2 cup of warm milk (110F), yeast and pinch of sugar and let it rest until fluffy.

Sift flour.

In a mixing bowl pour remaining 2 cups of warm milk, sugar, oil and vinegar.

Add about 1 cup of flour, mix and then add salt.

Keep adding remaining flour while mixing on low speed.

Transfer on floured surface and knead to shape a ball.

Transfer the dough to a lightly greased large bowl, cover with kitchen cloth and let it rest in warm place until double in size.

In a small bowl mix soften butter with the egg yolks.

Divide the dough into 3 parts and shape each into rectangle.

Using a rolling pin, stretch it to about 15 inches wide.

Spread the 1/3 of the egg mixture over the dough, cover with 1/3 of grated smoked mozzarella cheese, and then roll the dough jelly-roll style.

Repeat with remaining two portions.

Transfer the rolls to a baking sheet lined with parchment paper.

Cut the rolls into equal triangles. Leave to rise for at least half an hour.

In a small bowl mix the egg whites slightly and brush the bread. Sprinkle with sea salt or sesame seeds (optional).

Bake at 400F for 25-30 minutes.