Salmon isn’t a Mediterranean fish, but in this riff on a recipe from “Patricia Wells at Home in Provence,” high-impact Provençal ingredients are an ideal match for the rich, meaty fillets. We steam the fish atop a bed of sliced fennel to add sweet, licorice-like perfume; after cooking, the tender-crisp slices make a delicious accompaniment. The sharp flavors of the warm olive, caper and lemon vinaigrette complement both fish and fennel. We prefer salmon cooked to medium doneness—that is, until only the center is translucent. For well-done fillets, steam the fish for a couple minutes longer than indicated. If you prefer white fish over salmon, thick fillets of striped bass or sea bass work well, but increase the steaming time to about 10 minutes. No matter the type of fish you choose, try to select fillets of equal thickness so they cook at the same rate.