Preheat the oven to 375 degrees F.
For strawberry filling: In a large bowl, combine strawberries, lemon zest, lemon juice, sugar, cinnamon and cornstarch. Set aside to let the berries macerate and release their juices.
For crumble topping: In a small bowl, combine sugar, flour, oats, cinnamon and kosher salt. Shred in cold butter and mix together with a pastry blender or your hands until the mixture is crumbly and sandy
Transfer the macerated strawberries to a large casserole dish and top evenly with crumble topping.
Bake for 25-30 minutes, or until the top is golden brown and the sides of the crumble are bubbling.
Let the crumble cool for 5-10 minutes. Serve warm with vanilla ice cream.