To begin, in a small bowl, mix the warm water, sugar, and active dry yeast. Stir gently, then let sit for 5-10 minutes until frothy. This activates the yeast, ensuring your dough will rise properly.

In a large mixing bowl, combine the flour and salt. Pour in the frothy yeast mixture, lukewarm milk, and olive oil. Mix with a wooden spoon until the ingredients start to come together, forming a slightly sticky dough.

Transfer the dough to a lightly floured surface. Knead it for 8-10 minutes, adding a little flour as needed, until you achieve a smooth and elastic dough. Proper kneading develops the gluten, giving the koulouri their chewy texture.

Place the dough back into the bowl, cover it with a clean kitchen towel, and allow it to rise in a warm spot for about 1 hour, or until it doubles in size. This resting time is crucial for the dough to become light and airy.

Once the dough has risen, preheat your oven to 200°C (390°F) and line a baking sheet with parchment paper. In a shallow bowl, prepare 1/4 cup warm water, and in another bowl, spread the sesame seeds for coating.

Divide the dough into four equal portions. Roll each portion into a long rope, approximately 12 inches in length, and join the ends to form a ring. Press the ends together firmly to seal.

Dip each ring quickly in warm water, then immediately roll it in the sesame seeds, ensuring even coverage on all sides. Place each sesame-coated ring onto the prepared baking sheet, leaving space between each ring.

Bake in the preheated oven for 15-20 minutes, or until the koulouri are golden brown and crisp on the outside. Remove from the oven and allow to cool slightly on a wire rack. Serve warm or at room temperature, ideally with olives, cheese, or a drizzle of olive oil for dipping.