Cut kidney into 1-inch pieces. Boil kidney pieces in water for 20 minutes, changing the water two to three times. Set aside.
Preheat oven to 325º F.
Brown beef in oil in a 12-inch skillet over medium heat. Reduce heat and add onion; cook 5 minutes. Add flour, salt, pepper and thyme. Stir to coat meat. Add beef broth, wine, water and Madeira . Simmer 10 minutes to thicken sauce. Add the kidneys and mix well. Transfer to an over proof covered casserole dish. Bake at 325º F for 1½ hours or until meat is tender.
Sauté mushrooms in butter for 5 minutes. Add to meat mixture and continue cooking at 325º F for 30 minutes longer.
Preheat oven to 350º F
Line the bottom of 6 individual pie plates with pastry dough. Pierce the bottom. Spoon meat mixture into pie crust. Top with pie crust, sealing the edges all around. Pierce the top. (Note: The pies can be frozen at this point and baked later.)
Bake the prepared pies at 350º F for 30 to 40 minutes or until crust is golden brown and mixture is bubbly. Serve with steamed brussel sprouts. Yield: 6 pies.