[Sca-cooks] red wine substitute

[Heleen Greenwald]

I need to make a mushroom gravy for Shabbos and I found this recipe  
on Epicurious:
MUSHROOM GRAVY

Can be prepared in 45 or less.

1 pound mixed fresh white and exotic mushrooms such as cremini,  
oyster, or shiitake

  (discard shiitake stems)

4 large garlic cloves, minced

2 tablespoons unsalted butter

1 onion, chopped fine

1 tablespoon soy sauce

1/2 cup dry red wine

1 tablespoon balsamic vinegar

1 tablespoon cornstarch dissolved in 1 1/2 cups cold water

1/2 teaspoon sugar

2 tablespoons finely chopped fresh parsley leaves

Slice mushrooms. In a 10-inch heavy non-stick skillet cook garlic in  
butter over moderately low heat, stirring, until pale golden. Add  
onion and cook, stirring, until softened. Add mushrooms and soy sauce  
and sauté mixture over moderately high heat, stirring, until liquid  
mushrooms give off is evaporated and mushrooms begin to brown.

Add wine and vinegar and boil until liquid is evaporated. Stir  
cornstarch mixture and add to skillet with sugar. Bring mixture to a  
boil, stirring, and simmer 2 minutes. Stir in parsley and season  
gravy with salt and pepper. Gravy may be made 1 day ahead and  
chilled, covered. When reheating gravy, add water if necessary to  
thin to desired consistency.

Serve gravy spooned over baked or mashed potatoes and/or steak or  
chicken.

Makes about 2 1/2 cups.
Gourmet

My question: It calls for red wine. If I use wine, the wine MUST be  
kosher and I simply haven't got any kosher wine right now, or the  
ability to get any by Friday afternoon. What can I substitute for the  
red wine? Grape juice, in this instance is too disgusting to think  
about.  Perhaps some veggie broth? Anybody got any better suggestions?

Thank you in advance.
Phillipa