Preheat an oven to 450°F (230°C). 

 Cut the tomatoes in half and place them, cut side up, in a shallow baking dish. Season to taste with salt and pepper and drizzle 2 tablespoons of the olive oil over the tops. Bake until cooked through but still firm, about 15 minutes. 

 About 3 minutes before the toma­toes are done, in a sauté pan over high heat, warm 1 tablespoon of the olive oil. Add the shrimp and salt and pepper to taste and sauté until pink and firm, 2-3 minutes. 

 Transfer the baked tomatoes to individual serving dishes. Place the sautéed shrimp on top of the toma­toes, dividing them evenly. 

 In a small saucepan over high heat, combine the garlic and the remaining 3 tablespoons olive oil and sauté until the garlic turns golden brown, about 1 minute. 

 Add the vinegar and deglaze the pan by stirring to dislodge any browned bits from the pan bottom, about 30 seconds. Immediately pour the contents of the saucepan equally over each serving. Sprinkle with the parsley and cayenne. Serve at once.