Slice and dice rhubarb and strawberries. Add to a bowl. Combine sugar, cornstarch and vanilla and pour over berries. Mix well, you do not want the sugar white.

Place fruit in the bottom of a high sided 8×8 pan.

In another bowl, combine flour, brown sugar, sugar and oats. Add diced half cold butter and mix until crumbly. Crumble over the fruit mixture.

Bake at 350 degrees for 40-45 minutes.