SAUCE: Coat bottom of pot with vegetable oil. Cut whole garlic head in half; place both halves in pot with leaves. Cook for about 3 to 5 minutes. Add half bottle of soy sauce; once mixture reaches a boil, add the pound of butter. Simmer for 15 minutes.
FILET: Season each filet with salt, then sear in a pan. When filets are seared to desired doneness, remove from heat and allow to sit for 2 to 3 minutes. Make a small cut in center of filet, pour sauce over the top. Place a small amount of mustard on the side for dipping.