Rhubarb crisp

We were given some rhubarb, and I really wanted to make my MIL's rhubarb crisp. This is the recipe she uses most often. These amounts are for a 9x9 pan. Double for 9x13 (we doubled it). It is so sweet and tangy - yum.

1 c. flour
1 c. oatmeal
1/8 tsp. salt
1 c. brown sugar
½ c. melted margarine or butter
3½ c. chopped rhubarb

Mix all of the above ingredients except rhubarb, until combined and crumbly. Press ½ of the crumb mixture on bottom for crust. Spread rhubarb over top. In a small sauce pan mix together:

½ c. sugar
1 c. water
2 Tbsp. corn starch

Cook until thick and clear. Remove from heat and mix in:
red food color (it looks more appetizing)
1 tsp. vanilla

Pour evenly over rhubarb. Sprinkle remaining crumb mixture over top. Bake at 325° F for 1 hour. Serve w/ whipped topping or ice cream. You can cool it, or eat it warm.