When temperatures rise, anything that keeps you cool is welcome. Here’s a recipe for the perfect summer treat: Cucumber and yoghurt soup. It is a finely puréed cucumber mixed with Greek yoghurt and mayonnaise. Finely chopped cucumber pieces and mild spring onions add a little bite to the soup. The flavour is refined with a little olive oil, lemon juice and dill. If it’s really hot, you can add some ice cubes instead of water. If you want to add a portion of protein, serve with some boiled prawns or mildly smoked trout fillets as a garnish. A crusty baguette will provide a portion of satiating …