Onion-filled bialys

With a dough hook, mix 680 g flour, the cold water, 14 g salt and yeast on low speed for 3 min. Knead on medium-low for 6 min until elastic. Cover and rise for 90 min.

During the first rise, peel and very finely chop the onion. Put in a skillet with the oil and cook gently for about 25 min, stirring until lightly caramelised. Add the remaining 0.5 g salt and optional pepper. Transfer to a bowl, cool, then mix in the panko.

Put the dough on a clean, unfloured work surface. Divide into 12 equal pieces. Pull each piece's edges towards its centre, then turn seam-side down. Dust a tray with the remaining 10 g flour, place the rounds on it, cover and rest for at least 120 min until relaxed and puffy.

Towards the end of the rise, preheat the oven to 260 °C with the pizza stone on the middle rack. Prepare the high-temperature paper. Gently flatten the rounds to about 11.5 cm across, then press the centres with your thumbs to make hollows about 5.5 cm across. Thin the bottoms without piercing them and retain thick rims. Divide the onion filling among the hollows.

Slide half the bialys on their paper onto the hot stone and reduce the oven to 246 °C. Bake for about 10 min until well browned. Keep the remaining bialys covered while the first batch bakes, then bake them in the same way. Cool on a rack for about 10 min and serve.