• 4 oz (110 g) potatoes, cooked and puréed
• 12 oz (350 g) plain flour
• 2 heaped tablespoonfuls fast-action yeast
• 1 teaspoon sea salt
• 7 fl oz (200 ml) warm water
• 8 tablespoons good quality olive oil
• 12 oz (350 g) red onions, thinly sliced
• Rosemary (optional)

Mix the flour with the yeast, salt, potatoes, water and 4 tablespoons of the olive oil. Make a dough, adding more flour if necessary and knead until smooth. (This can be done in a food processor).

Place in a covered bowl and leave to rise in a warm place until doubled in size – this takes about 1½–2 hours. Meanwhile heat the remaining 4 tablespoons of oil and, over a very low heat, leave the onions to soften in this for about an hour.

Knock the dough back and press into an oiled 12 x 8 inch (30 x 20 cm) tin. Leave to rise again for about 20 minutes and then with a spoon make a few depressions on the surface of the dough.

Spread over the onion mixture and scatter the rosemary over the surface. Bake at gas mark 6/400°F/200°C for about 25–30 minutes until golden brown. The base should sound hollow when tapped.