Dijon Mushroom Potatoes

1 medium onion
1 sweet green bell pepper
1 small carrot
1/2 lb. mushrooms
1/2 cup stock or boullion
1 tbsp. dark soy sauce
1 tbsp. Dijon mustard
1 tbsp. cornstarch
freshly−ground black pepper

Chop the onion, deseed and chop the green pepper, peel
and grate the carrot and slice the mushrooms, halving them
across the other way first if they are large.