Make your pie dough by combining flour, salt, sugar in either a mixing bowl or a food processor. Add your butter either by hand (crumbling the cold butter into the flour until it your butter is broken down into smaller than pea sizexchunks or it resembles sand) or in the food processor (add your butter and pulse until the mixture resembles sand).
Add ice water (just very cold water) and pulse or combine by hand until the dough starts to stick together. It's okay if it's still a little crumbly, but if it's not coming together at all, add another tablespoon of ice water.
Wrap up your dough in plastic wrap and chill for at least 30 minutes.
Meanwhile, chop up your rhubarb. Make sure to remove any leaf bits and only use the stem.
Once the 30 minutes for the dough to chill are almost over, preheat your oven to 420 F (215 C). Add your rhubarb, sugar, vanilla extract, pinch of salt, and flour to a large mixing bowl and combine.
Take your dough out of the fridge. Take 2/3 of the dough and roll out into a large circular shape to fit the pie tin. We used a 9.5 inch glass pie pan for this pie!
Transfer your pie dough to the pie tin by rolling it around the rolling pin and unrolling over the tin.
Fill in any bare spots by patching it up using some of the excess dough hanging over the edge.
Pop your pie pan into the freezer while you prepare the lattice, just to keep it cool. Roll out the remaining 1/3 of the dough.
Cut into strips about 3/4 inch wide.
Take your pie pan out of the freezer and add the rhubarb filling. Now start by taking your longest strips and placing them across the center of the pie.
Add more strips and interweave them by lifting up on the already placed strips in an over/under pattern.
Trim the edges of the lattice and crimp the edge all around with a fork. Once you have finished the lattice, put the pie back into the freezer for about 5 minutes. Once it has chilled, brush with heavy cream and a sprinkle of sugar. You can also use an egg wash!
Bake for 15 minutes at 420 F (215 C). Lower the temperature to 350 F (176 C) for about 45 minutes. If your edges are getting too dark, cover the area with foil. If the pie seems very liquidy after 45 minutes, raise the temperature to 400 F (204 C) for about 10 minutes, making sure that the filling is bubbling. When the filling boils, the flour should thicken the liquid that may have been released by the rhubarb. Remove from the oven when the crust is fully baked and the rhubarb filling has thickened slightly (it will also thicken more when it cools down).