In large bowl, stir granulated sugar and flour or cornstarch until blended. Add blueberries and lemon juice; stir to coat evenly. Spoon blueberry mixture into shallow 2-quart glass or ceramic baking dish; spread evenly. Sprinkle the lemon peel over the berries. The tartness of fresh lemon peel balances the sweetness of the berries and topping, so use the amount that suits your personal taste.
Combine flour, oats, brown sugar, butter, and cinnamon. With fingers, mix until coarse crumbs form. Crumble over blueberry mixture.
Place sheet of foil underneath baking dish; crimp foil edges to form a rim to catch any drips during baking. Bake crisp 35 to 40 minutes or until top is browned and fruit is bubbly at edges. Cool on wire rack 1 hour to serve warm or cool completely to serve later.