1: Peel, rinse and chop 1 spring onion (scallion) finely. Rinse, dry and chop parsley and coriander . The quantities are approximate: say 2-3 tablespoons of each. Chop the chives finely, including the flowers if you can to add extra flavour and an attractive touch of colour.
2: Put the herbs into a bowl and add 350 g Greek yoghurt. Otherwise, you can use cream cheese or unsweetened fromage frais.
3: Add 2 tablespoons Herb olive oil (or simply plain olive oil, if you don't have any) and the juice of ½ lemon. Salt lightly and pepper generously.
One interesting possibility with this sauce is the hot-cold contrast: piping-hot baked potatoes, split open with a spoonful of really cold sauce in the middle - simply delightful! Make plenty at a time, as it is always popular.