Preheat the oven to 400 degrees F.
Warm the oil in a large skillet over medium heat. Add the onion and sauté until soft and fragrant, about 5 minutes. Add the Vadouvan paste and stir to combine.
Add the cauliflower and allow it to brown slightly, cooking about 3 minutes. Add the remaining vegetables and vegetable broth. Increase the heat, bringing the mixture to a boil. Reduce heat to simmer and cook until the vegetables and warm all the way through and the broth slightly reduced. Sprinkle on the potato starch and stir until combined. Remove from heat.
Line a 9" pie pan with bottom crust and transfer the vegetable mixture on top. Cover with the top crust and pinch the edges closed.
Bake at 45 minutes, until the crust is browned and the filling is bubbling and piping hot! Allow the pie to rest 5 minutes before serving.