Stuffed Zucchini with Tomatoes and Mozzarella

INGREDIENTS

• Olive oil, for brushing baking sheet
• 2 medium zucchini
• Coarse salt and ground pepper
• 2 plum tomatoes, halved, seeded, and diced small
• 1/4 teaspoon chopped fresh oregano leaves
• 1/4 teaspoon white vinegar
• 5 ounces fresh mozzarella, torn into 1-inch pieces