Place vegetables (carrots, onions and potatoes) around the roast.
In a bowl mix together remaining ingredients in a bowl and then pour over roast.
Cook roast on high for 4-6 hours or low for 6-8 hours until it has reached desired tenderness.
When roast is done, remove it and vegetables from the crock pot ,and use a portion of the remaining liquid to make a sauce.
Sauce:
Combine together in saucepan:
2 cups of the liquid from crock pot 1 envelope of onion soup mix.
In a small cup mix 1 tbsp corn starch and 1 tbsp water until dissolved. Add to saucepan and continue to cook and stir the sauce until it has thickened.