Preheat the oven to 350 F. Lightly grease a small baking dish (I used one that was 6.5 x 7 inches, but any small size will do!).
Cut the stems off the strawberries and slice them in half vertically. For strawberries that are especially large, you can slice them into 3 vertically. Add the sliced strawberries to a large bowl.
Squeeze the lemon juice over the strawberries and sprinkle the cornstarch and brown sugar on top. Using your hands, gently toss to combine, until all of the strawberries are coated well. Set aside.
In a separate bowl, add the oats, flour, brown sugar, vanilla extract, and salt. Pour the coconut oil on top. Using your hands, mix everything together. You can gently rub the mixture together using your fingertips to help it set.
Sprinkle the flour and oat mixture over the strawberries and gently press it down.
Bake in the preheated oven for about 30 minutes, until the oat mixture has browned and the strawberries have softened.
Top with whipped cream or vanilla ice cream and serve.