Chervil-Butter Sauce for Fish

Chervil is the most fragile of common herbs, hard to find in the supermarket but beloved by chefs and gardeners; when you see it, grab it. (You can achieve something of the same effect by combining parsley and basil.)

Because this sauce contains flour, it is leaner and easier to make than Béarnaise, but it still has great flavor. Serve it over poached or grilled fish.