Prepare the starter: Dissolve the yeast, sugar, and flour in warm water. Let sit for 5-10 minutes or until the mixture starts bubbling. If the surface looks still after 10 minutes, discard and start over with new yeast.

Prepare the dough: In the bowl of stand-in mixer, stir the flour, sugar, milk, egg, butter or oil, and sea salt with a wooden spoon. Add the starter, then knead using the dough hook of the mixer on low to medium speed for 8-10 minutes. The dough is ready when it no longer sticks to the bowl and starts rolling around the hook. The dough should be soft and barely sticky. Cover with a towel and let the dough rise in a warm, draft-free area, until doubled in size, about two hours.

Shape the dough: Punch down the dough and, using a dough scraper, transfer to a clean, lightly floured, kitchen surface. Divide the dough in 2 equally sized balls and let them rest for a couple of minutes. Roll each piece into a log, then shape into a coil. Transfer to two baking sheets covered with a silicon mat or parchment paper, leaving several inches of space between two coils. Cover loosely with a kitchen towel and let rise until almost doubled in volume, about 90 minutes.

Bake: Brush the tops with egg wash, sprinkle with sesame seeds, and transfer to an oven preheated to 350°. Bake until golden brown, about 45 minutes. Cool on a rack and serve warm or at room temperature.

For rolls, divide the dough into 8 balls after the first rise and proceed with the recipe, making sure to decrease the baking time to 30 minutes.