Unlike other fruit crisps, you don’t have to worry about mushy strawberries in this recipe.  The strawberries will either be soft and tender or breaking down into a chunky syrup.  If the strawberries are soft and mushy before you even cook with them, then they are starting to decompose and best used for strawberry syrup or jam instead.  If you’d like more of a strawberry jam filling, you can still use them in this recipe, adding 1 extra tablespoon cornstarch.