Blueberry, Apple, Rhubarb, Lemon (ok let's call it Fruit) Crumble

I was going to make blueberry crumble but found that someone had used some of the berries I was planning on using.  So I substituted half the berries with other fruit.

Start by adding these ingredients to a saucepan.  Heat for a few minutes.

1 1/2 cups blueberries
1 1/4 cups apples, chopped
1/2 cup rhubarb, chopped
1/2 cup sugar
zest and juice of 1 lemon
1/3 cup water

Next take 2 tbsps. cornstarch and mix it with 2 tbsps. cold water in a cup.  Take a tbsp. or 2 of the hot mixture and stir it in.  Now pour it into the saucepan stirring well as you pour. 

Simmer 10-15 minutes, uncovered, to thicken.  Cool.

In a large bowl mix:

2 1/2 cups oats
1 1/4 cups whole wheat flour
1 cup brown sugar
1/4 tsp salt
(you can also add 2 tbsps. ground flax)

Blend in using a pastry cutter or 2 knives,
3/4 cup margarine or butter

Have an 8 X 8 inch pan greased or lined with parchment.
Press well 2/3 of the oat mixture into the bottom of the pan.

Spread the fruit filling on top then sprinkle on the balance of the dry mixture.  Press lightly.

Bake at 350F for 30-35 mins.
Cool before cutting.

Serve plain or with whipped or ice cream.