Rhubarb slices

1. I'll start with the filling. I'll put the rhubarb, strawberries and lemon juice in a saucepan, mix, cover with a lid and cook over low heat for a few minutes, stirring occasionally,
until the fruit is slightly softened. I mix the sugar with the cornstarch and add it to the fruit. I keep stirring the fruit until it starts to boil again and then thickens in about a minute. I remove the saucepan from the heat.
2. Preheat the oven to 180°C. In a large bowl, mix the flour, oatmeal, sugar, baking powder and salt. Then add the butter and rub it in with your fingers until it forms crumbs. Set aside about a cup and a half of the crumbs, and press the rest into the bottom of a greased 26 x 36 cm baking tin. Spread the filling evenly over the dough and sprinkle with the crumbs I set aside, and bake for 30–35 minutes. Wait for it to cool, looking forward to the first piece the whole time.