Start by prepping the pie crust, roll it out and place it in your pie dish. Crimp the edges and let it rest in the fridge.
Now for the streusel topping: stir together the flour, sugars and salt in a bowl. Crumble the butter and rub it in with your fingers, just until the mix is chunky but not completely homogenous. Rest it in the fridge for 15 minutes as you prepare your fruit.
Preheat the oven at 200°C. In a large bowl, mix your sliced fruit with lemon juice, sugar, cornflour, spices, salt and bitters and combine.
Pour the filling in the pie crust and top it with the streusel topping.
Bake it on the lowest part of the oven for 20-25 minutes. Once the pie starts to get golden, reduce the temperature to 180°C and bake for a further 30 minutes, or until the juices are bubbling and the topping is of a deep golden brown colour.
Allow to cool down fully before serving.
Notes
The plum streusel pie will keep refrigerated for 3 days or at room temperature for 2 days.