• 125 g (4½ oz) desiree potatoes, cut into 3 cm (1¼ inch) cubes
• 20 ml (½ fl oz/1 tablespoon) olive oil
• 110 g (3¾ oz) white starter
• 225 g (8 oz) organic wholemeal (whole-wheat) flour
• 225 g (8 oz) organic plain flour
• 8 g (¼ oz/3 teaspoons) sea salt
• 5 g (⅛ oz) fresh yeast
• 300 ml (10½ fl oz) water
• 4 rosemary sprigs, leaves picked

Preheat the oven to 220°C (425°F/Gas 7). Put the potato cubes in a baking tray and pour over the oil. Season with salt and freshly ground black pepper and bake in the oven for 15 minutes, or until you can almost pierce them all the way through with a knife — the potatoes only need to be half-cooked at this stage as they will continue cooking when the loaf is baked. If the potatoes are overcooked they will disintegrate when you go to fold them through the dough. Imperfection is often the signature of a handmade product. If it has potatoes spilling out when you cut the loaf, you know only the human hand could have achieved that.

To mix the potato bread by hand, put the white starter in a large bowl with the wholemeal and plain flours, sea salt, yeast and water. Mix together with a large spoon until the mixture comes together to form a dough, about 5 minutes. Turn out onto a clean work surface and knead into a ball with your hands for about 15 minutes, or until smooth.

If you are using an electric mixer, put the white starter in the bowl of the mixer with the dough hook attachment. Add the wholemeal and plain flours, sea salt, yeast and water. Mix on slow speed for 4 minutes. Scrape down the sides of the bowl then continue mixing on high speed for 6 minutes or until smooth (it will not be elastic).

When the dough is properly developed fold through the potatoes and rosemary, either by hand or very gently on the slowest setting of your mixer.

Lightly grease a container with oil spray and sit the dough inside. Cover with plastic wrap and set aside at ambient room temperature (approximately 20°C/68°F) for 1 hour to bulk prove.

To knock back the dough, turn it out onto a lightly floured surface and press out into a rectangle, about 2.5 cm (1 inch) thick. Use your hands to fold one-third back onto itself, then repeat with the remaining third. Turn the dough 90 degrees and fold it over again into thirds. Place the dough back into the oiled container and continue to bulk prove for a further 30 minutes.

Use a blunt knife or divider to divide the dough into two even-sized portions, about 500 g (1 lb 2 oz) each. Working with one portion of dough at a time, continue to shape the loaves following the instructions for shaping a round loaf.

Line two small baskets with a tea towel (dish towel) in each, lightly dust both with flour and place a loaf inside each, seam side up. If you are using a traditional cane basket, you don’t need the tea towel and can simply dust the basket with flour. Alternatively, you can place the loaves on a baking tray lined with baking paper, seam side down. Place in the refrigerator loosely covered with a plastic bag for 1 hour.

Preheat the oven to its highest temperature. Remove the loaves from the refrigerator and let them rest in a humid place (25°C/77°F — this could take anywhere between 1 and 4 hours — until each loaf has grown in size by two-thirds. If the loaves push back steadily and quickly when you push lightly into them with a finger then they are ready. Score the loaves and place them in the oven.

Spray the oven with water and reduce the temperature to 220°C (425°F/Gas 7). Bake the loaves for 20 minutes, then turn the loaves or trays around, and bake for a further 10 minutes, watching carefully to make sure that the loaves do not burn. Check the base of each loaf with a tap of your finger — if it sounds hollow, it is ready. Baking should take no longer than 40 minutes in total.