For fondue de poireau : blanch the
leek in salted water for 4 minutes. Drain,
cool in an
ice bath, drain again, and dry on absorbent paper. In the meantime, melt the
butter in a saucepan over medium heat. Add the onions and sweat until tender and lightly colored. Add the cooked leeks,
cream,
salt, and
pepper.
Cook, while stirring constantly, until creamy.