Preheat oven to 375°F. Place the pie plate on a rimmed baking sheet (important, it will bubble).
In a large bowl, toss together the strawberries, citrus juice, granulated sugar, salt, vanilla, and cornstarch until evenly coated. Let sit for 5 minutes to start releasing juices.
In a separate bowl, whisk together brown sugar, granulated sugar, cinnamon, flour, and salt. Pour in melted butter and stir until clumps form. It should look crumbly, not sandy.
Pour the strawberry mixture into the 8-inch pie plate, spreading evenly.
Sprinkle the crumble evenly over the top, lightly pressing larger clumps together.
Bake for 30-35 minutes, until filling is bubbling around the edges and topping is golden brown.
Cool slightly (10-15 minutes) before serving so the filling thickens.