Caramelized Onion, Beet and Feta Tart - Margot Dreams of Baking

Ingredients

• cups all-purpose flour
• tbsp sugar
• tsp salt
• tbsp unsalted butter, cut into 1/2 inch cubes and chilled
• tbsp water
• tbsp olive oil
• medium onions, halved and sliced thin
• cups grated beets
• tsp salt, divided
• tbsp chopped fresh rosemary or thyme
• tbsp balsamic vinegar
• cup feta cheese, crumbled
• large eggs
• cup half-and-half cream
• tsp black pepper