Preheat the oven to 375(f) degrees. Cut pie dough in half & roll each piece out on a lightly floured surface to a 10-inch disc.
Transfer one disc to a 9-inch pie plate. Shape to form crust & trim the edges.
In a large mixing bowl toss together the berries, rhubarb, sugar, lemon juice, vanilla, cornstarch & salt. Toss evenly to combine. Transfer filling to prepared crust.
Top fruit filling with the remaining disc of dough & flute the edges. You can also create a lattice top if desired.
Brush with egg wash & sprinkle generously with raw sugar. Chill for 15 minutes before baking (this will help the crust hold its shape better while baking).
Bake until the fruit begins to bubble & the top is golden, about 45 to 50 minutes.