1. Heat 1/2 teaspoon oil in a small skillet over moderate heat until hot but not smoking. Add pine nuts and cook, stirring until golden brown, about 2 minutes. Transfer nuts to paper towels to drain, and season to taste with salt.
2. Whisk together vinegar, capers, and garlic and add remaining 6 tablespoons oil in a slow stream, whisking until combined. Stir in herbs, mozzarella, and tomatoes and let stand at room temperature, stirring occasionally, for at least 15 to 30 minutes.
3. Cook pasta in a large pot of boiling salted water until almost tender. Reserve 1/4 cup cooking water and drain remaining pasta in a colander.
4. Immediately transfer hot pasta and reserved cooking water to bowl with marinated mozzarella and tomatoes, and let stand 1 minute.
5. Gently toss pasta and cheese mixture and season with salt and pepper to taste. Serve immediately, sprinkled with pine nuts.