In a large pan, saute the onions in 1/2 of the olive oil until they're translucent and then set aside.
In the same pan, add the tofu and the other 1/2 of the olive oil and tumeric and fry until browned (or slightly browned). Mix in onions, bag of frozen vegetables and boiled potatoes. Pour mixture into pie crust bottom and set aside.
Preparing the cheese sauce:
In a small pot, whisk the butter and flour together on medium heat for 1 - 2 minutes.
Add the milk and continue stirring/whisking until it thickens...this may take a while, just keep on stirring...
When good thickness, between a yogurt and sour cream thickness, has been reached, add the cheese and stir until melted. Then add the horseradish, hot sauce and garlic.
Pour mixture evenly over the tofu/vege mixture and cover with the other half of the pie shell, crimp.
Bake at 350 for 1/2 hour to 45 minutes or until crust is browned.