Mix all the ingredients for the levain and let it ferment 3-5 hours, or until it has at least doubled in volume.

Mix the levain with all the rest of the ingredients, except egg, poppy seed, and oats, and let it rest for 20 minutes.

Knead the dough for 5-10 minutes and let it rest for an additional 30 minutes. Perform a set of stretch and fold if necessary.

Let the dough bulk ferment until it has increased by about 75% in volume. It should have a slightly domed surface and preferably som gas bubbles on top.

Dump out the dough on a floured working surface and divide the dough into 6 pieces with equal weight.

Shape the dough pieces into rolls and place them in a greased oven tray. Cover with cling film and let the rolls proof overnight, or about 8 hours, in the refrigerator.

Preheat the oven to 480°F/250°C in good time before baking

Brush with beaten egg and sprinkle with poppy seed and oats. Bake for 20-25 minutes. You may have to lower the temperature for the last 10 minutes.