FOR THE CRUST
If you have a food processor, this is a good job for it: Pulse together the oats, brown sugar, salt, and melted butter just until mixed.
If you are mixing by hand, just stir the whole works together.
Pat about 2/3 of the crust mixture into a 9-inch pie plate, going up the sides as far as you can. I used a deep-dish pie dish, so if you use a regular sized one, no worries – you’ll just have a little more topping left over. It worked pretty well to use a big tablespoon and coax the oats up the sides of the dish, so if your oats are not cooperating, you might try that strategy. Set the remaining topping aside until ready to bake.
FOR THE PIE
Preheat your oven to 425 degrees.
In a smallish bowl, stir together the Minute Tapioca (or cornstarch) and water. Let stand and do its thing for about three minutes. The reason for this exercise is to allow the tapioca or cornstarch to dissolve, and form for lack of a better word, a slurry.
In a Dutch oven sized pan, stir together the rhubarb, sugar, and salt. Stir in the tapioca (or cornstarch) and water slurry. Bring to a boil over medium heat, until thickened and bubbling, and let it boil for about one minute. NOTE: The rhubarb will not be tender or cooked through – this is a good thing. The first time I tried this recipe I decided to cook the rhubarb until it was soft…and then it disintegrated. The pie still tasted great but didn’t look all that hot).
Once the mixture is thickened, remove from heat and gently stir in the strawberries, just until mixed.
Spoon the mixture into the crust and sprinkle the remaining topping over the top of the pie. You might have too much filling if you aren’t making a deep-dish pie, which is another good thing. Just spoon it into a bowl and grab the ice cream!
Bake for 20-35 minutes, depending on whether you are using a deep-dish pie pan or not. The filling should start to bubble, and the pie should look like it is thickened and set. Check on the pie’s progress after about 15 minutes. If it looks like it’s getting too brown on top, spray a piece of aluminum foil with cooking spray and lay it gently over the top of the pie to prevent burning. That should do the trick.
Cool to room temperature before diving in. I refrigerated it overnight before slicing and it was good as gold the next day.