Preheat the oven to 425F and butter a glass pie plate or small gratin pan.
Add the strawberries and rhubarb to the pan and mix well.
Combine the oats, brown sugar, flour, cinnamon and butter in a bowl (use your hands, they work best) until the butter is worked through and you are left with a crumbly mixture.
Spread the oats mixture evenly over the fruit and bake for 20 minutes or until the juices are bubbling and thick and syrupy and the oats are golden brown.
Enjoy on its own or with a scoop of your favourite ice cream.
To make the Overnight Rhubarb Sauce – place 8 cups of sliced rhubarb in a saucepan and stir in 1 cup of cane sugar. Leave overnight. Bring the mixture to a simmer the next day and simmer until the liquids are thickened and syrupy (about 20 minutes). Turn off the heat and add 1 teaspoon of vanilla. Cool completely and store in the fridge or freeze.