Dijon Mushroom Potatoes (Low-Fat)

1 med. onion - chopped
1 med. green bell pepper - seeded, chopped
1 sm. carrot - peeled, grated
1/2 Lb. mushrooms - sliced
1/2 cup beef stock
1 Tbls. soy sauce
1 Tbls. Dijon mustard
1 Tbls. cornstarch
fresh ground black pepper - to taste
4 baked potatoes

In a large frying pan, sauté the vegetables in the stock until most of the liquid is gone and the vegetables are soft. Mix the remaining ingredients together in a bowl, adding a bit of water if you wish (makes a thinner sauce) and add to the vegetables in the pan. Mix well and cook, stirring constantly, over low heat for about a minute until thickened. Pour over hot, split baked potatoes.