Rhubarb Pie-Tartlets

INGREDIENTS

• :
• 2 cups all-purpose flour
• ½ cup cornmeal
• 1 teaspoon salt
• 1 teaspoon granulated sugar
• 1 cup (8 ounces) unsalted butter, cold, cut into small pieces
• ¼ to ½ cup ice water
• 1 to 1½ pounds rhubarb (about 5 cups ½-inch diced)
• ½ cup granulated sugar
• ¼ cup light brown sugar
• ¼ cup cornstarch
• ¼ teaspoon salt
• ½ teaspoon vanilla extract
• 1 egg, lightly beaten (for the egg wash)
• Sanding sugar or granulated sugar, for sprinkling