In a large bowl place the water, milk, yeast, sugar and mix with a spoon. Let stand for 10 minutes for the yeast to activate.
After it has rested, add the egg white, vegetable oil and mix very well with a wooden spoon. Add the sifted flour, salt, and mix with the same spoon and then with your hands until a very sticky dough forms. Cover the bowl with a kitchen towel and let the dough rest for 20 minutes.
Place the dough on the clean counter and knead it by beating and folding it over itself for 10 minutes until it takes more shape. It is important not to add more flour as the kneading is what will shape the dough (the whole kneading process can also be done in a mixer with the dough hook).
Once ready, form a ball with the dough and put it in a clean bowl with a little oil so that it does not stick. Cover with a kitchen towel or plastic wrap and let the dough rise for 2 hours to double in size.
Once the dough has doubled in size, place it on a clean, floured counter and divide it into 2 equal parts. Form 2 balls with each piece of dough, cover them with a kitchen towel and let them rest for 20 minutes. Meanwhile, in a small bowl, mix with a fork the egg yolk with the 2 tablespoons of milk and then glaze the breads.
Preheat the oven to 190° C and place a large tray in the middle of the oven to heat up. Take one of the dough balls, place it on a large piece of baking paper and spread it with your hands with a little of the egg yolk mixture. With the same hands, carefully flatten the dough until it is flat in a circular shape with a diameter of approximately 20 cm.
Spread the dough again with the egg yolk mixture and make a border around the edge of the circle, as if it were a pizza. Then draw lines with your fingers in the center of the circle: there should be 3 parallel lines and then 3 lines crossing the previous ones. Repeat the same process with the other ball of dough.
Once both loaves are ready, brush them using a kitchen brush with more egg yolk mixture, sprinkle them with sesame seeds and place them on the tray that had been put in the oven to bake for 25-30 minutes until they are well browned.
Remove the breads from the oven and let them cool for at least 15 minutes and then enjoy.
The bread will keep perfectly at room temperature for up to 2 days or in the refrigerator for up to 1 week. After day 1 it will become a little hard, so it is good to reheat it in the oven at 150° C for 10-15 minutes until it is softer.