3 1/2 pounds sirloin tip roast, trimmed
1/4 cup flour
2 teaspoons salt
1/8 teaspoon pepper
3 medium carrots, peeled and sliced
3 medium potatoes, peeled and quartered
2 small onions, sliced
1 stalk celery, cut in 2" pieces
1 (2 ounce) jar mushrooms, drained or 1/4 Cup mushroom gravy
3 Tablespoons flour
1/4 cup water
Trim all excess fat from roast; brown and drain if using chuck or another highly marbled cut.
Combine 1/4 cup flour, the salt and pepper.
Coat meat with the flour mixture.
Place all vegetables except mushrooms in slow cooker and top with roast (cut roast in half, if necessary, to fit easily).
Spread mushrooms evenly over top of roast.
Cover and cook on Low for 10 to 12 hours.
If desired, turn to High during last hour to soften vegetables and make a gravy.
To thicken gravy, make a smooth paste of the 3 Tablespoons flour and the water and stir into slow cooker.
Season to taste before serving.