Celeriac and Egg Mousse

This mousse can conveniently be made a day or two in advance and kept in the refrigerator. The grated celeriac is delicious combined with eggs and mayonnaise, and provides a good contrasting texture. You can decorate the top of the mousse with black olives and anchovies, or do as my sister Camilla does, and serve it with black olive pâté – fairly easily obtainable from delicatessens – spread on slices of toasted French bread. The mousse makes a very good supper dish to follow a hot soup.