With cooking spray, grease 6 (or 8) pint-sized wide mouth mason jars. Set aside. Preheat your oven to 350 degrees F.
In a large bowl, mix together the rhubarb, strawberries, sugar, corn starch, and lemon juice. Set aside.
In another larger bowl, whisk together the flour, sugar, salt, and baking powder. Using a pastry blender (or your fingers) cut the butter and vegetable shorting into the dry ingredients until crumbly.
Beat the egg and milk together in a small bowl. Pour this into the flour mixture and stir with a fork until just combined.
Evenly divide the strawberry rhubarb mixture into the mason jars. Then, tear off pieces of the dough and drop them onto each portion of the fruit. Sprinkle the dough lightly with sugar.
Place filled jars onto a baking sheet. Bake for 20-25 minutes or until the top is golden and the fruit is bubbly. Carefully remove from the oven. Allow to cool. Serve warm with a big scoop of vanilla ice cream.