Preheat your oven to 350°F (175°C). This ensures that the crumble cooks evenly and the strawberries soften perfectly.

In a large mixing bowl, combine the sliced strawberries, granulated sugar, cornstarch, vanilla extract, and lemon juice. Toss gently to coat the strawberries evenly. The sugar will draw out the juices from the strawberries, creating a delicious filling.

Transfer the strawberry mixture into a 9-inch baking dish, spreading it out evenly.

In another mixing bowl, combine the all-purpose flour, oats, brown sugar, cinnamon, and salt. Mix well to ensure the dry ingredients are evenly distributed.

Pour the melted butter into the dry mixture. Using a fork or your fingers, mix until the mixture resembles coarse crumbs. This will create a crunchy topping when baked.

Sprinkle the crumble topping evenly over the strawberry filling in the baking dish.

Place the baking dish in the preheated oven and bake for 25-30 minutes, or until the topping is golden brown and the strawberries are bubbling. This allows the flavors to meld and the topping to become crispy.

Once baked, remove from the oven and let it cool for about 10 minutes before serving. This cooling time allows the juices to settle, making it easier to serve.