My latest culinary discovery and invention! I had some lovely fresh salmon fillets, a fennel bulb and lots of potatoes.....so, I thought I would make a one dish meal out of it. Everyone loved it and it is light enough to eat any time of the year. Do try to use WHOLE boned & skinned salmon fillets - they sit so well lengthways in your gratin dish! I added no garlic to mine - I felt that the fennel and onion flavours were enough; but if you like, a clove or two at the most might be a tasty addition. Serve with chilled Chablis, Colombard,Chardonnay or a good Rose wine for a delightful lunch or supper. We ate this with crusty bread and a big bowl of mixed salad.....plus a couple bottles of wine! This serves 6 people as a main meal, but it can be reduced or increased according to your menu requirements.