Peel and cut the cucumber into small pieces. Add salt and rub it into the cucumber pieces with your hand. Cover and let stand for 30 to 45 minutes. Place the cucumber pieces on a cheesecloth or a few paper towels and squeeze the excess liquid out.

Place in a food processor and purée it. Combine with yogurt, lemon juice and garlic. Season with salt and freshly ground black pepper. Refrigerate for 1 hour for the flavours to mingle. Taste and adjust the seasoning if needed.

The sauce can be made ahead and kept in a tight jar for 2 to 3 days. Give the mixture a stir before using.