Rhubarb Coffee Cake and Breakfast Potluck - Turntable Kitchen

Ingredients

• 2 tablespoons cornstarch
• 2 tablespoons sugar
• 1 teaspoon ginger, grated
• 1/2 cup all-purpose flour
• 3/4 cup packed light brown sugar
• 1 teaspoon ground ginger
• 1/2 teaspoon ground cinnamon
• 1/4 teaspoon salt
• 6 tablespoons (1/2 stick) unsalted butter, cold and cut into small pieces
• 1/2 cup sour cream
• 1 large egg
• 1 large yolk
• 1 teaspoon vanilla extract
• 3 cups all-purpose flour
• 2 teaspoons baking soda
• 1 teaspoon baking powder