Prepare your pie crust. If you make our Everyday Flaky Pie Crust recipe, double the 9-inch recipe and divide in half to roll out the top and bottom crusts. You may also want to add 1 teaspoon of dried thyme leaves to the dough with the other ingredients--it adds a nice savory flavor to the whole pie.
Roll out the bottom crust and place in pie plate. Trim around so the edge extends a little less than an inch from the edge of the pan. Set aside top crust dough.
Preheat the oven to 400 F/205 C.
In a large saucepan, combine broth, chopped vegetables, and spices. Bring to a boil, and cook at a slow boil until vegetables are soft. Stir cornstarch into 1/4 cup cold water, then add to the saucepan. Stir for 2-3 minutes, until broth thickens. If using, cook meat, then chop into bite sized pieces, and either add to saucepan or set aside. Do the same for tofu. (When I make both vegetarian and meat versions at the same time, I sprinkle the protein into the pie shell as I'm filling it--a layer of stew, a layer of protein...repeat.)
Roll out the top crust.
Grate or slice cheese, if using, and layer half of it over the bottom crust. Then spoon in the filling. Cover with another layer of cheese, if using. Before placing the top crust over the pie, dampen the edge of the bottom crust with either water or some of the broth--it helps to seal the crusts together. Place the other crust on top, then fold the edges of the top crust over the edges of the bottom, and pinch/crimp around the entire pie to seal. Cut several slits in the top crust to allow steam to escape as the pie cooks.
If freezing, let the pie cool, then cover well with foil and place in freezer. (Also something to think about if you're making this ahead of time to freeze it--you might want to let the cooked vegetables and sauce cool down to room temperature before putting the pie together.) Be sure to thaw the pie fully before baking.
Bake at 400 F/205 C for about 60 minutes, until crust is golden brown and juices are bubbling through the slits (you may have to reopen them near the end of the cooking to see the bubbling--just slide your knife through them again).
Allow the pie to cool for about 15 minutes, then serve. The filling will be really runny when freshly cooked, but will thicken up when it's completely cooled.