Preheat the oven as high as it will go. (For most ovens, that's 500 degrees .)
Season the fish with salt and pepper. Stuff each with some lemon slices, 2 cloves crushed garlic, a few herb sprigs and a bay leaf. Drizzle the outside of the fish with olive oil; season.
Pour 1/3 cup olive oil in a large roasting pan. Add the tomatoes, shallots, vermouth, a few thyme sprigs and the remaining crushed garlic; toss. Arrange the fish on top. Place the halved lemon in the pan, cut side down.
Roast until the fish is flaky and opaque and the tomatoes are soft, 15 to 18 minutes. Douse the fish with the juice of the roasted lemon.
Divide the tomatoes among plates. Using a serving fork and serving spoon, carefully lift the fillets away from the bones; arrange on top of the tomatoes. Serve with bread.