Slow Cooker Dilled Pot Roast

Ingredients
1/3 cup all purpose flour
1/2 tsp kosher salt
1/4 tsp freshly ground pepper
2 tsp vegetable oil
2 1/2 pounds beef roast, rump, chuck or arm cut
2 tbsp dijon-style mustard
2 onions, peeled and cut into eighths
2 carrots, peeled and sliced into 1-inch pieces
1 celery rib, with top, cut into 1-inch pieces
2 garlic cloves, peeled
1 tsp dill seed
1/2 tsp peppercorns
1/4 cup nonfat, low sodium beef stock
1 tbsp red wine vinegar

Sauce
cooking juices from beef
3 tbsp instant flour
1 tsp dijon style mustard
1 tsp dill weed
1/2 cup lowfat sour cream

Directions
Combine flour with salt and pepper.  Coat beef with flour mixture, shaking off excess.  Heat oil in 12 inch skillet over medium-high heat; brown beef on all sides.  Transfer to platter or cutting board; cool for a few moments.  Rub mustard evenly over all sides of the beef.
Place onions, carrots, celery, garlic, dill seed and peppercorns in the slow cooker.  Top with mustard-coated beef.  Pour in stock and vinegar.  Cover and cook on low for 10-12 hours.
Remove beef, transfer to storage container, strain and discard vegetables.  Pour cooking juices over beef; cover and refrigerate overnight.  One hour before serving, remove beef (reserve juices), and cut off visible fat.  Place in a small roasting pan and reheat for 30-45 minutes at 325 degrees.  Strain cooking juices into a saucepan, discard fat.  Add flour, mustard and dill weed; stir over medium heat until sauce comes to a boil and thickens.  Remove from heat, cool briefly and stir in sour cream.  Taste for seasoning and add 1/4 tsp salt if desired.  Cut meat into thin slices; pour some sauce over the top and pass the rest into a sauceboat.