Butter and yolk sauce

• 1/4 lb/125 g butter
• 5 yolks
• juice from 1 lemon
• salt

In a small pan, placed in a larger one with boiling water, mix the butter, adding the yolks one by one. Stir continuously until hot, but do not let boil. Add salt and lemon juice. Serve on steamed vegetables or boiled potatoes with a pinch of fine chopped dill  on them.