2 (1 1/4 - 1 1/2 lb.) flank steaks
1/2 c. soy sauce (low sodium)
1/2 c. oriental sesame oil
3 tbsp. red wine vinegar
Fresh ground pepper
2 med. garlic cloves, crushed

Place in non aluminum pan. Whisk soy, oil, vinegar and generous amount of pepper in medium bowl. Cover pan tightly and refrigerate 24 hours, turning steaks occasionally. Barbecue high heat 4 minutes per side (medium rare). Transfer to platter and let rest 5 minutes.

MUSHROOM SAUCE:

1 lb. mushrooms
3 tbsp. unsalted butter
3 tbsp. vegetable oil
2 c. unsalted beef stock
4 tsp. Dijon mustard
1/2 c. whipping cream
1 tbsp. unsalted butter
1 tbsp. vegetable oil

Cut mushrooms. Melt butter and oil over medium high heat. Add mushrooms, stir 3 minutes. Mix in 1 cup stock and mustard. Increase temperature to high and boil until half reduced, about 5 minutes. Add 1 cup stock, 1/4 cup at a time, boiling until sauce is reduced by half each addition. Stir in cream. Boil until sauce coats spoon, about 3 minutes. Season with salt and pepper. Can be prepared day ahead.