Preheat the oven to 350°F.
In a medium bowl, mix brown sugar, flour, oats, soda, salt, and vanilla. Add melted butter and stir until combined. Press half the oat mixture into the pan and bake for 10 minutes.
While the crust bakes prepare the strawberry filling. Mix together strawberries, cornstarch and sugar.
Remove bar crust from oven. Place strawberry filling over the base. Crumble the remaining topping over the strawberry filling. Return the bars to the oven.
Bake for 25 minutes. Cool on the counter for about 45 minutes. Cover and chill in the fridge for at least 4 hours before cutting and serving.