Roast Beef without guinness juice

2 tablespoons butter 1 small onion , thinly sliced 2 tablespoons whole grain mustard 1/2 loaf ciabatta, split lengthwise 1/3 lb thinly sliced deli roast beef[...]

2 lbs roast 1/4 cup red wine 1 teaspoon butter or 1 teaspoon margarine 3 large potatoes , halved and quartered 1/2 lb baby carrots 1/2 cup red bell pepper ,[...]