Blackberry and Blueberry Crumb Bars | Food Stuff

Ingredients

• 1 cup blackberries
• 1 cup blueberries
• 2 tablespoons cornstarch
• 2 cups all-purpose flour
• 1/2 teaspoon ground cardamom
• 2 tablespoons fresh lemon juice
• 1 teaspoon lemon zest
• 1 1/4 cups light brown sugar, firmly packed
• 2 cups oats (quick or old-fashioned -- I used a mix of both)
• 1/2 teaspoon salt
• 1/4 cup sugar
• 1 cup unsalted butter, cold and cut into small pieces
• 3 tablespoons water