1. Pre heat the oven to 180c. Peel the rhubarb. Cut the rhubarb into 1 inch pieces and place in a pot with the strawberries, 120g castor sugar and the lemon zest, place on the stove over a medium heat and cook for 10 minute or until the rhubarb just starts to soften and collapses. Then place in a baking / serving dish.
2. For the crumble, in a bowl place the butter, 100g castor sugar, flour and oats and mix together to for a rustic, chunky crumble then place on a baking tray and cook in the oven for 10 minutes or until golden. Remove from the oven and sprinkle over the rhubarb mix. Reduce the oven temperature to 160 c.
3. To serve place the rhubarb back in the oven for 5-10 minutes the remove and garnish with the chards of crispy rhubarb, serve with some clotted cream or custard.
