Savory Pork Stew with Potato Dumplings

1/2 teaspoon pepper

1 1/2 teaspoons olive oil

1 jar (12 ounces) pork gravy

1 tablespoon Dijon mustard

1 tablespoon red wine vinegar

1 tablespoon Worcestershire sauce

1/8 teaspoon ground red pepper (cayenne)

1 bag (1 pound) frozen broccoli, red peppers, onions and mushrooms

1/2 package (7 1/5-ounce size) Betty Crocker® butter & herb mashed potatoes

1 1/4 cups hot water

1/2 cup milk

2 tablespoons butter or margarine

1 egg, beaten