And, yes, though it's often cooked as a fruit rhubarb is actually a vegetable (just try stewing a little with pork to see what I mean).
For wild food enthusiasts you can make this with the new stems of Japanese knotweed as well. Just peel the stems before use then substitute them for the rhubarb.
Rhubarb CrumbleServes: 6
For the Fruit:1kg (2 lbs) rhubarb
1 tbsp water
2 tbsp caster sugar
For the Crumble Topping:75g (3 oz) plain flour
50g (2 oz) butter
25g (1 oz) oats
50g (2 oz) soft light brown sugar
1/2 tsp ground cinnamon
Method:Trim the ends off the rhubarb and cut into chunks (no need to peel). Place the rhubarb in a saucepan with the water and sugar then bring to a simmer, cover and cook gently for about 4 minutes or until just softened.
Turn the rhubarb mixture into the base of a greased 1l (4 cup) shallow ovenproof dish then set aside as you prepare the topping.
For the topping, place the flour in a bowl then rub the butter into the flour until the mixture resembles breadcrumbs. Stir in the oats, sugar and cinnamon. Sprinkle the resultant mixture over the fruit then transfer to an oven pre-heated to 170ºC (340ºF, Gas Mark 5) and bake for between 30 and 35 minutes, or until the top of the crumble is golden brown.
Serve hot, accompanied by custard.