Onion tart - Domaines Vinsmoselle

Ingredients

• 250 g of flour
• 125 g of cold butter, cut into small cubes
• A pinch of salt
• 4 to 5 tablespoons of cold water
• 4 to 5 medium-sized onions, thinly sliced
• 2 tablespoons of olive oil
• 2 tablespoons of butter
• 2 eggs
• 200 ml of thick sour cream
• Salt and freshly ground black pepper
• A pinch of nutmeg (optional)