Bourride

First make a fish stock. Heat together in a heavy pot: 1 pound bones from white-fleshed fish, washed and cut into pieces, 1/2 leek, white part only, cleaned, sliced, and rinsed, 1/2 small onion, sliced, 1/2 fennel bulb, trimmed and sliced, 4 garlic cloves, peeled and smashed, 3/4 cup dry white wine, A few black peppercorns, 1 bay leaf, 2 or 3 thyme sprigs, A big pinch of salt, 4 cups water.

Bring to a boil and then turn immediately down to a simmer. Skim well and cook for 45 minutes. Strain through a fine sieve; discard the bones and vegetables.

While the stock is cooking make a very rich garlic mayonnaise. Mix together: 2 egg yolks, 1 teaspoon water.