Traditional wisdom is not to cook tomatoes in cast iron, because Iron is a very reactive metal. The tomatoes can potentially pick up the metallic flavor. This will not be an issue if the pan is well seasoned, in our experience.
1. Heat broiler. Preheat a large, heavy ovenproof skillet (preferably cast iron) on top rack for 15 minutes. Meanwhile, toss together tomatoes, beans, capers, garlic, 1 tablespoon oil, and 1/2 teaspoon salt in a bowl. Toss shrimp with remaining tablespoon oil and 1/4 teaspoon salt in another bowl.
2. Remove skillet from oven, and add tomato mixture. Broil until tomatoes are charred and beginning to collapse, about 5 minutes. Remove from oven, and stir in stock, then shrimp. Broil, stirring halfway through, until shrimp are opaque, about 3 minutes more. Drizzle with oil.