I love rhubarb! And this is a great pie! If you whant you can also use frozen puff pastry! Just let it thaw completely & use like a pie crust! You may wanna roll it out a little thinner. It will be SUPER flaky (LIKE ME!!)
Open the piecrust package (it will unroll easiest if you leave it out for about 15 minutes but if you leave it out too long they will stick together).
Place your bottom piecrust layer in a 9" pie pan. The edges will hang over. That's fine. We'll get to that later.
n a large bowl mix the rest of the ingredients except the other piecrust. Toss the cherries and the rhubarb real well.
Now spoon that mixture in the crust. It will pile higher than the edges but should not run over.
Now place the last crust over the top. It will also have edges that hang over. What I do next is lightly wet the lower piecrust INSIDE edge to make the two piecrusts stick together-this acts like glue. Do this in about 3" sections, then roll the excess piecrust under so it has the seams turned under on the pie pan. Finish this all the way around and then do the old-fashioned thing and just finish sealing the pie by pressing the tines of the fork all around the pie edge. Lastly take your fork and poke a couple of holes in the pie toward the top center so air can escape while the pie cooks.
Bake at 425 degrees for 35 minutes and you should have a beautiful, light brown-crusted pie. Eat warm, room temp or refrigerate and eat cold.