Italian Pot Roast

1 (2 1/2-pond) boneless beef round roast
1 medium onion, sliced
1/4 tsp. Salt
1/4 tsp. Pepper
2 (8-ounce) cans no-salt-added tomato sauce
1 (0.7-ounce) package Italian salad dressing mix

Slice roast in half and place in a 3 1/2 quart electric slow cooker. Add onion and remaining ingredients. Cover and cook on high setting 5 hours or until roast is tender. Or, cover and cook on high setting 1 hour; reduce to low setting and cook 7 hours. Slice meat to serve.