French Onion Pan Quiche - Today's Parent

Ingredients

• 2 cups all-purpose flour
• 1/2 tsp salt
• 3/4 cup cold unsalted butter, cubed
• 1/4 cup ice water
• 1 tsp white vinegar
• 1 tbsp canola oil
• 2 red onions, thinly sliced
• 1/2 tsp granulated sugar
• 6 eggs
• 1/2 cup 35% cream
• 1/4 cup milk
• 2 cups grated Gruyere
• 1 tsp thyme leaves