Crust: pulse the flour and salt together twice in a food processor.

Add the butter in one-inch chunks and pulse 4-6 times.

Beat together egg yolk and vinegar with a fork in a one cup measure and add ice-cold water to fill to one-half cup.

Drizzle on top of flour and butter while pulsing 24-30 times.

Divide the dough into two parts, pat into circular flat disks and wrap tightly in food wrap, chill for one hour in the fridge before rolling out 1/8 thick.

Place first layer of crust in a lightly greased pie pan.

Filling: combine chopped rhubarb and sliced strawberries, sugar, tapioca, and vanilla in a large bowl and mix together so fruit is coated in sugar and tapioca.

Let sit for an hour before spooning fruit into the prepared pie shell.

Top with pats of butter, the second crust, brush with water and sprinkle with a tablespoon of sugar.

Bake in a pre-heated oven at 425 degrees for 20 minutes, then turn oven down to 350 degrees and continue to bake 40-50 minutes until crust is golden and filling is bubbling.

Let cool for an hour (or two!) before slicing.