1 eye of round 2- to 4-pound
1 onion large, thickly sliced
1 package au jus gravy mix
1/2 cup vermouth
2 tablespoons cornstarch
1 1/2 tablespoons water cold
1/4 teaspoon basil dried, crushed (optional)
1/4 cup sour cream
Heat oven to 250° F. Place eye of round in a 1 1/2 - to 2-quart baking dish. Cover with onion slices. Prepare au jus according to package instructions; mix 1 1/2 cups au jus with vermouth and pour over meat. Cover and bake for 3 to 4 hours. Just before meat is done, remove, slice, and keep hot. Strain juice into saucepan. Combine cornstarch with 1 1/2 tablespoons water and blend into sauce along with optional basil. Heat, stirring, until clear and thick. Blend in sour cream and serve along with meat.