1. To make the pizza bases, mix the yeast with 200 millilitres of lukewarm water. Add the castor sugar, stir, and set aside for 10 minutes. Mix the flour and one teaspoon of salt in a bowl, and make a well in the centre. Slowly add the yeast mixture to the flour, drawing in the flour with your fingers until the dough forms into a mass. Add  two tablespoons of olive oil, and continue to mix until all the oil is absorbed.

2. Turn out onto a floured work surface, and knead the dough until it is smooth and no longer sticky, about 10 minutes. Transfer to a clean bowl, cover with a clean tea towel and leave in a warm place for two hours.

3. In the meantime, cook the potato whole in simmering water for 10 minutes. Drain, cool and finely slice (unpeeled) into rounds. Tear any larger mushrooms in half and toss in one tablespoon of olive oil with the red onion. Tear the kale leaves into bite-sized pieces and massage with one tablespoon of olive oil.

4. Heat the oven to its highest setting. Divide the dough in half, roll out two pizza bases, brush with remaining oil, and arrange the sliced potato, torn mozzarella, oyster mushrooms, red onion and grated fontina on top.

5. Bake for  five minutes, then scatter with kale leaves and bake for a further five minutes or until crisp. Cut into wedges and serve with chilli oil.