First prepare the crumble for the topping. Put the flour, rolled oats, sugar and pinch of salt in a bowl and mix everything with your hands. Then add the softened butter in pieces and make a firm dough. Work with your hands to make coarse crumbles. The consistency should be very thick and crumbly. If the dough is too liquid, add a little more flour. Put the crumble in the fridge until you are ready to use it.
Wash strawberries and cut off the stalks, halve them. Put them in a bowl and mix in the lemon juice and scratch the contents of vanilla pod into it.
Now grease the baking dish with butter or vegetable oil and pour in the strawberry mixture. Using your fingers, crumble the crumble evenly in a layer over the strawberries. The surface should be covered.
Bake the strawberry crumble for about 30 minutes until the surface is golden-brown. Take it out of the oven, let it cool slightly and serve warm with custard or vanilla ice cream.