Preheat the oven to 180°C (350°F) and line a square 20 cm square (8 inch) baking tin with parchment paper.
In a large bowl, combine the oat flour and oats, coconut sugar, and salt. Add the coconut oil, almond butter, and vanilla and stir until everything has been incorporated and it holds together when pressed. Reserve one third of this mixture for the topping.
Evenly crumble the remaining oat mixture into the prepared baking pan, and press firmly with your hands to make the base. You can use a small rolling pin or wet hands to make an even layer.
Add the strawberry mixture and spread it over the base layer. Crumble the reserved oat mixture over the strawberry filling. Bake at 180°C (350°F) for 35-40 minutes, or until golden.
Cool fully in the tin before removing and slicing into bars. Store in the refrigerator or freezer.
Strawberry Filling
Place the strawberries in a shallow bowl (you might have to do this in two batches) and mash them with a fork. It doesn't need to be perfectly smooth. Stir in the arrowroot, lemon juice, and maple syrup (if using). Alternatively, use an immersion blender to mix. It will thicken as it bakes and turn into jam.
600 grams ripe strawberries, 2 teaspoons arrowroot powder, Juice of half a lemon, 1 tablespoon maple syrup
Notes
* You can substitute a scant 2 cups of store-bought oat flour for homemade. To make your own, blend the oats in a food processor for a minute or two until a flour forms.