Vegetable Tarte Tatin

INGREDIENTS

• 1 tablespoon fresh oregano leaves
• 3 tablespoons extra-virgin olive oil
• 2 medium sweet potatoes, peeled and cut into 1/2-inch-thick rounds
• 1 8.5-ounce sheet frozen puff pastry, thawed
• Kosher salt and freshly ground pepper
• 1 tablespoon white wine vinegar
• 1 small onion, cut into 1/2-inch-thick rounds
• 6 ounces mozzarella, grated (about 1 cup)
• All-purpose flour, for dusting
• 1 tablespoon small fresh sage leaves
• 3/4 cup sugar
• 2 medium parsnips, peeled and cut into 1/2-inch-thick rounds
• j2 medium Yukon gold potatoes, peeled and cut into 1/2-inch-thick rounds
• 4 cloves garlic, halved