First, begin the sourdough pizza base. Prepare this in the morning, leave it in a warm place to rise, and it will be ready in the evening for cooking.
Combine all the pizza ingredients to form a very moist dough.
250g plain white flour
150g sourdough starter (50% flour, 50% water)
1 beaten egg
70g runny yoghurt
20g olive oil
Turn the dough out onto a work surface and knead for at least ten minutes; it is quite wet and sticky initially, but will get smoother as the gluten develops. Return the dough to an oiled bowl with plenty of room for expansion, as it is very vigorous, cover and leave in a warm place for at least six hours or until needed.
An hour or so before you wish to eat, turn on the oven to a high heat: 250 degrees (or 500 degrees F, Gas Mark 10). Place a baking tray or cloche into the oven to heat. This amount of dough makes two 25cm pizzas.
6 large leeks
2tbs olive oil
Now prepare the leeks. Wash them thoroughly and cut into coins (not too thick; keep plenty of green leaf as well as the white stems). The leeks should be softened gently in olive oil over a very low heat; stir frequently to avoid burning or browning.
Only add the salt at the end of the cooking time to prevent the leeks becoming mushy and colourless. This should take 20 - 30 minutes, but may take longer.
Knock the pizza dough down. Divide the mixture in half and turn out the first half onto a well floured surface, adding more flour on top of the dough. Gently shape it into a round and place it on the heated tray. Spread half the cooked leeks across the surface of the pizza and than plop teaspoonfuls of labneh on top of the leeks.
Bake for 20 - 30 minutes or until the base is crusty and brown. Eat while still hot or warm.
Labneh (or labne) is a Middle Eastern salted, strained yoghurt with the sourness of yoghurt, but more like cream cheese in texture. The word labneh meaning "white" is from the same root as the name for Lebanon. Unlike other cheeses, it doesn't melt when baked, which suits this particular pizza.