Slivers of Chicken Breast and Fennel with a Balsamic Vinegar Sauce

This is a quickly made but excellent dish; it completely transforms chicken breasts which, although lean and tender, are often dull and dry. Not so here, combined with moist and mellow fennel in a cream sauce perfected by the unique sweet sharpness of balsamic vinegar. Serve with tagliatelle or waxy new potatoes and a green vegetable such as broccoli or petits pois.