Stir together first 8 ingredients and ½ tsp. salt in a bowl until well blended.
Sprinkle fish with pepper and remaining ½ tsp. salt. Cook in 1 Tbsp. hot oil in a heavy sauté pan over high heat 1 minute on each side (rare) or to desired degree of doneness. Transfer fish to a plate, and let stand 3 minutes. Cut into 4 equal pieces.
Divide Roasted Tomatoes among 4 individual serving plates. Top with fish, and drizzle with desired amount of vinaigrette. Reserve any remaining vinaigrette for another use.