Heat the soy milk until almost boiling, mix cornstarch with enough water to make a thick mixture. Whisk into soy milk. Stir and bring to a boil, keep whisking, turn down to simmer and add salt and pepper, simmer until thickened. Remove from heat. Set aside.
Preheat oven to 375 degrees F.
In a medium bowl, combine cream-sauce, and vegetables.
Spoon filling into bottom pie crust. Cover with top puff-pastry crust, and crimp edges to seal. You can be pretty rustic with puff pastry and it still looks good, just cut and shape to fit approximately. Slit top crust.
Bake for 40 minutes or until deep golden brown. Remove from oven, and cool for 10 minutes before serving.