Step 1

You need exactly 300g/10½oz to make the bread so check the weight once they are peeled. Place the potatoes in a large saucepan and cover with cold water, bring to the boil, then reduce the heat slightly and cook for 15–20 minutes until they are tender but not falling apart.

Step 2

Drain the potatoes in a colander over a bowl and reserve the cooking liquid. Return the potatoes to the pan and toss over a very low heat for 2-3 minutes until any excess liquid has evaporated.

Step 3

Pour 75ml/5 tbsp of the warm cooking liquid into a large bowl and leave to cool for a few minutes. When it’s lukewarm, sprinkle in the yeast. Stir in the sugar and leave in a warm place for about 10 minutes until a light foam appears on the surface. If you’re using a mixture of wholemeal and white flour, add an extra tablespoon of the cooking liquor.

Step 4

Mash the potatoes with the oil in the saucepan until they’re as smooth as possible, then stir in the yeast mixture and salt.

Step 5

Mix well with a wooden spoon and gradually add the flour, a few tablespoons at a time, stirring well before adding more. When the dough becomes too stiff to stir in the flour, turn it out on to the work surface and knead the remaining flour into the dough. Don’t be tempted to add more water or the dough will become too sticky to work with.

Step 6

Knead the dough for 10 minutes until soft and pliable. Place it in a lightly oiled bowl, cover loosely with lightly oiled cling film and leave to rise in a warm place for 45–60 minutes, or until well-risen and spongy to touch.

Step 7

Knock back the dough with your knuckles and shape it into a rough ball. Flatten the ball on a floured surface until it is about 2cm thick, then bring the sides up to the middle to give a rustic surface to the bread. Pinch lightly to seal and sprinkle on some wholemeal flour, for additional texture, on the outside of the loaf. Place it on a lightly oiled and floured baking sheet, rough-side up, and leave to prove in a warm place for a further 30 minutes.

Step 8

Preheat the oven to 220°C/Fan 200°C/Gas Score the dough with a knife along the pinched join and sprinkle the top with the onion seeds. Bake the loaf in the centre of the oven for 35 minutes until well risen and crusty on top. Cool on a wire rack.