Blueberry Apple Rustic Tart

3-4 apples, peeled, cored, and sliced
1 cup blueberries, fresh or frozen
lemon juice
1/4 cup flour
2-4 tablespoons sugar
1 teaspoon cinnamon
pinch salt
pie crust for single crust pie
butter

Place peeled and sliced apples in a big bowl and sprinkle with lemon juice. Add blueberries, flour, sugar, cinnamon and salt; mix well. Roll out crust and place flat on a cookie sheet or baking dish, use a fork to dock the bottom of the crust. Pour apple mixture into center of crust and dot with butter. Fold edges of crust over the sides of the mixture, leaving the center open. Brush the crust with water or milk and sprinkle with cinnamon sugar. Bake at 450 for 20-25 minutes.