1. Preheat oven to 450°.
2. Place bread in a food processor; pulse until fine crumbs measure 1 cup. Combine breadcrumbs, parsley, and garlic. Heat 2 teaspoons butter and 2 teaspoons oil in a large skillet over medium-high heat. Add breadcrumb mixture; cook 3 minutes or until golden brown and garlic is fragrant, stirring frequently.
3. Coat 4 individual gratin dishes with remaining 2 teaspoons oil. Arrange shrimp in a single layer in dishes; sprinkle with dash of salt and dash of pepper. Sprinkle with 1/2 cup breadcrumb mixture; top with tomato slices. Sprinkle with remaining dash of salt and dash of pepper. Top with remaining 1/2 cup breadcrumb mixture; dot with remaining 2 teaspoons butter. Bake at 450° for 12 minutes or until the shrimp are done. Drizzle with vinegar.