In a medium sized saucepan over medium heat, pour in the beef broth and add the diced potatoes. Cook until almost completely tender; about 10-15 minutes.
Add in the frozen vegetables and heat through, simmering for about 5 minutes.
Line the bottom of your pie plate with one of the pie crusts.
Lower one of your oven racks to the second from the bottom position and pre-heat your oven to 350 °F.
Dissolve the cornstarch into the water completely, then whisk into the gravy mixture rapidly, until smooth and thickened. Taste, and adjust salt, pepper and perhaps more beef bouillon accordingly. Stir in the chopped beef.
Pour the gravy vegetable mixture into the pie plate and gently smooth into one layer.
Place the remaining pie crust on top and pinch the edges to seal shut, Cut a couple of pie vents into the surface.
Bake in a preheated oven until the crust is golden brown, about 45-60 minutes. Let cool for 5 minutes before serving.
If you enjoy more gravy, add another 1/2 cup of beef broth. We like our pie a little more firm, but a thinner gravy is also great!
Make sure to bake the pie on the lower oven rack as suggested. This is what cooks the bottom pie crust!