Put the dry yeast in 1 cup warm milk with 2 tbsp flour and 1/2 tbsp sugar. Beat 2 eggs with the yoghurt, oil, vinegar and salt. To the wet ingredients, add the already effervescent yeast and start adding flour slowly.
Stir and add flour until it becomes difficult to stir with a spoon. Start kneading, while still adding flour, to obtain a soft, stretchy dough that doesn't stick to the hands.
Cover it in the container so it doesn't dry up and form a crust. Leave it to double in volume. Then take it out and roll out into a large ellipse. Cut the lower half into strips, smear the upper half with the butter that you've heated on the stove.
Start rolling it up from the buttery side to obtain a roll. Lift it carefully and put in a pre-greased tray, arrange in a spiral. Let it rise again, smear with egg yolk and sprinkle on the seeds.
Place in a preheated 302°F (150 °C) oven and turn the heat up to 338°F (170 °C) as soon as you've placed it in the oven. Bake until reddened. The loaf becomes as soft as cotton - guaranteed results!