Method

At Home

1. Combine the flour, 1 cup of the sugar, and salt in a zip-top freezer bag.
2. In a second bag, combine the remaining 1/4 cup sugar and cornstarch.

At Camp

1. Prepare a cooking fire.
2. Combine raspberries, blackberries, the sugar and cornstarch mixture, and lemon zest in a 10-12 inch dutch oven and mix well.
3. Cut the butter into small cubes and add it to the zip-top bag with the flour mixture. Close the bag and massage the bag until the mixture looks crumbly and the butter is incorporated.
4. Crumble the dough on top of the berry mixture.
5. Cover the dutch oven with its lid and place in a bed of hot coals. Cover with the lid, and place coals on lid (see this temperature chart to get a 375 degree oven).
6. Bake until the juice from the fruit is bubbly and the topping is golden brown.