Place the tomatoes, olives, capers and garlic on the same baking sheet. Drizzle with 1 teaspoon olive oil, 2 tablespoons vinegar and 1 teaspoon thyme. Place in oven and roast until just beginning to soften, about 15 minutes.
In a small bowl, mix the remaining 2 teaspoons olive oil and 1 teaspoon thyme, 2 tablespoons vinegar, ¼ teaspoon salt, and pepper to taste; brush on the fish. Place fish atop roasted tomato mixture and return to oven until fish is just cooked through, about 10 minutes.
Divide among plates and serve with the potatoes. Garnish with sprigs of thyme.
Nutrition information per serving:
Calories325Fat11 gSodium734 mgSaturated fat2 g
Carbohydrates26 gCalcium68 mg