Preheat the oven to 350°F. Grease a 10-inch oven-safe skillet, 2-quart baking dish, or 9×9-inch square baking dish. Set aside.
In a large bowl, add the strawberries, sugar, lemon juice, vanilla extract, and cornstarch. Stir until well combined.
Pour the berry mixture into the prepared baking dish.
In a medium bowl, combine the flour, brown sugar, oats, cinnamon, and salt. Use a pastry blender or fork to cut the butter into the oat mixture until it becomes crumbly.
Then, using your clean fingers, press the mixture into larger clumps until all the flour mixture is fully incorporated into the butter.
Sprinkle the oat mixture evenly over the strawberries.
Bake for 40 to 45 minutes, or until the topping is golden brown and the strawberry juices are bubbling around the edges.
Remove the crisp from the oven and set it on a wire rack to cool for about 5 minutes before serving. Serve warm with vanilla ice cream, if desired.
