French Tomato Tart - Maison Maitland

Ingredients

• 1 sheet Puff Pastry*
• 4 tablespoons mayo
• 1 tablespoon sunflower oil
• 1 cup onions (sliced)
• 1 clove garlic (minced)
• 1/4 teaspoon kosher salt
• 2 - 3 medium tomatoes (thinly sliced)
• 1 cup Gruyere cheese (shredded)
• 2 sprigs of thyme (about 1 teaspoon)
• 2 tablespoons unsalted butter (melted)