This soup is a beautiful, serene green and can be made very quickly if you have some left over potatoes. I’ve still got a few cucumbers in the garden, together with plenty of cos lettuce and it seems appropriate to prolong the summer by serving them in a warming autumn soup, rather than the traditional chilled cucumber soup. I left out any garlic which makes it an inoffensive lunch-time dish. I used vegetable stock to give a vegetarian, gluten and dairy free soup. Makes about four servings.
One telegraph cucumber (about 500g in weight), diced – no need to peel
150-200g cos lettuce leaves, well washed, dried and roughly chopped
Three large spring onions, sliced – use about the same amount of the green parts as there are white
150g cooked potoato without the skins – left-over roasters work well
Knob of butter or tablespoon of olive oil (if you want a dairy free version)
Two cups (500ml) vegetable stock
Heat the butter or oil in a large heavy bottomed saucepan. Toss in the cucumber, lettuce and onion and stir over a medium heat until the lettuce has wilted. Add the potato to the pan, put the lid on and cook over a low heat for about ten minutes. Check and stir after a few minutes to make sure it’s not catching on the bottom of the pan. Add the vegetable stock and bring to a simmer. Remove from the heat and blend with a stick-blender in the pan or process in batches in a food processor. Check the seasoning – it may need more salt and pepper, depending on the saltiness of your vegetable stock.