Strawberry Rhubarb Filling: Combine rhubarb, strawberries and lemon juice in 3 quart saucepan. Cover and simmer over medium heat, stirring occasionally, 8-12 minutes or until fruit is tender.
Combine granulated sugar and cornstarch in bowl. Stir into fruit mixture. Continue cooking, stirring constantly, 1 minute or until mixture comes to a boil. Continue to boil for an additional 1 minute or until thickened. Remove from heat. Set aside to cool slightly.
Preheat oven to 350°F. Spray a 13x9-inch baking pan with cooking spray. Set aside.
Crust: In a large bowl use a whisk to sift together the flour, oats, brown sugar, granulated sugar, baking soda and salt.
To the bowl add softened butter. Using an electric mixer on medium speed, beat just until it comes together and resembles crumbs.
Remove 1 1/2 cups of the crust mixture to a separate bowl. Mix with the pecans for the crumble topping. Set aside.
Press the remaining crust mixture evenly onto the bottom of the prepared pan.
Layer: Spread the cooked fruit evenly over the crust. Sprinkle the top with the crumb-pecan mixture.
Transfer to the oven and bake 30-35 minutes or until golden brown. Cool completely in the pan on a wire rack.
Make the Glaze: In a small bowl whisk together the powdered sugar, heavy cream and vanilla. Drizzle over cooled bars then slice and serve.