Preheat the oven to 350°F (175°C). Grease the baking pan.

In a mixing bowl, combine flour, sugar, melted butter, salt, and oats. Mix until crumbly.

Press half of the mixture into the bottom of the prepared pan to form the crust.

In another bowl, combine sliced strawberries, chopped rhubarb, sugar, cornstarch, and vanilla extract. Mix well.

Spread the filling evenly over the crust in the baking pan.

Sprinkle the remaining crumb mixture over the filling.

Bake in the preheated oven for 35-40 minutes or until the topping is golden brown.

Allow to cool before slicing into bars.