Ingredients
50g butter
3 tablespoons olive oil
4 medium leeks, trimmed, cut in half lengthways, washed, drained and thinly sliced
1 teaspoon Turkish chilli flakes or paprika
1 rounded teaspoon dried mint
1 egg
2 teaspoons plain flour
350g home-made or Greek yoghurt
500ml water or Chicken Stock
caramelised butter (see note below)
sea salt and black pepper


Method
Place a large saucepan over a medium heat and add the butter and olive oil. When the butter begins to foam, stir in the leeks. After 10 minutes add the chilli flakes or paprika and dried mint, and continue to cook the leeks for another 20-30 minutes, stirring occasionally until they are sweet. Set aside.

In a large bowl, whisk the egg with the flour until a smooth paste is formed. This will stabilise the yoghurt when it is heated. Now stir in the yoghurt and thin with the water or stock. Pour on to the leeks and return the saucepan to the heat. Gently heat the soup over a low to medium heat, stirring every now and then. Do not allow the soup to boil, but remove from the heat just before it bubbles. The soup should have a smooth, silky quality, about the consistency of single cream. Check for seasoning and pour the caramelised butter on top.

Variation: When wild garlic leaves are in season, substitute them for leeks. Sauté in olive oil until sweet and tender, chop finely and add to the soup along with 75g cooked white rice.

Note: Caramelised butter is regularly used in Turkish cooking, often twinned with yoghurt. The combination is simple yet magical. To serve four, place 75g unsalted butter in a small saucepan and set over the lowest heat. As the butter melts, the whey will separate. Continue to heat gently, stirring occasionally, until the white bits turn golden brown. This gives the butter a wonderfully nutty, caramelised aroma, but be careful the bits do not get too dark as they will burn easily.