This is a fantastic salad, prepared in no time at all, and at very little cost. Serve it with warm nan bread and one or two other interesting salads.
Drain the flageolets and reserve a little of the liquid. Mix the pesto with 1 tbs of the liquid, adding more if necessary to bring to a mayonnaise consistency. Dress the flageolets in the pesto mixture, and fold in the mushrooms. Mix well. Leave to stand at room temperature for an hour or two before serving. Heap on to soft lettuce leaves lightly dressed with vinaigrette and serve.
