Preheat oven to 375º. Spray an 9x9 baking dish with non-stick cooking spray.

Mix sugar, cornstarch, and salt in large microwave-safe bowl. Mix in water and rhubarb. Microwave on high, stirring occasionally, for about six minutes or until the rhubarb is tender and liquid has thickened. Stir in strawberries, zest, and food coloring if using. Spread in the prepared dish.

In a large bowl combine brown sugar, flour, oats, almonds, ½ teaspoon cinnamon and ¼ teaspoon salt. Add melted butter and mix with a fork or your hands until mixture resembles crumbly wet sand. Sprinkle mixture evenly on top of strawberry rhubarb filling.

Place baking dish on a rimmed baking sheet, and bake until filling is bubbling around the edges, and topping is golden brown about 25 minutes. Cover top with foil if the top is getting brown before the filling is bubbling. Let rest 20 minutes before serving.

Serve warm from the oven topped with a scoop of vanilla ice cream, if desired.