Steam the potatoes with a sprig of dill and when tender, put them in a warmed dish with a little chopped dill. Serve with the following sauce, ensuring the ingredients are at room temperature:
Beat the egg yolks and then beat in the mustard, lemon juice and squeezed garlic (use a garlic press). Then add the oil, drop by drop, until the sauce thickens. Towards the end the oil can be added faster. Season and add a tablespoon of boiling water. Whip the cream and fold into the mayonnaise.