Mix all filling ingredients into a large mixing bowl and set aside.

Combine flour, brown sugar, salt and oats into a medium size mixing bowl and stir to combine.

Add the coconut oil and stir to thoroughly mix until mixture resembles coarse crumbs.

If using vegan margarine, make sure it is cold and you cut it in with a pastry blender or a fork.

Spray a 9×13 size-baking dish with a non-stick baking spray.

Give the rhubarb mixture another stir and then pour into the prepared baking dish.

Sprinkle the crumb mixture evenly over the top.

Place in a 350-degree oven for 50-55 minutes or until fruit is bubbly and topping is golden.

Allow to cool a little bit before serving.