1. Pre-heat oven to 190°C/375°F/Gas 5.
2. To stew apples and rhubarb: peel, core and roughly chop apples and roughly chop rhubarb. Place in saucepan with a little water (1 tablespoon approx) and place over a low heat, stirring occasionally until apples and rhubarb are softened. When soft, if liked, add a pinch of cinnamon.
3. Place the flour, sugar and oats into a bowl.
4. Add margarine and rub into the dry Ingredients with tips of your fingers to form a crumble.
5. Place the apples, rhubarb and berries in an oven-proof dish and sweeten with sugar.
6. Spread crumble over the apples.
7. Bake in the oven for 20-30 minutes approx.
8. Serve hot with cream, ice cream, custard, yoghurt or cr̬me fraiche.

Note: apples and rhubarb can also be stewed in a microwave. Place fruit and water in a deep microwaveable bowl and cook on high for approx 5 minutes, stirring occasionally.