i cook my roast thawed or frozen, frozen holds and seals in the juices best! sprnkle your garlic on the roast cover it well..i also use a cajun seasoning as well...(Louisiana's fish fry products, Cajun Seasoning) add enough oil the over bottom of dutch oven and Brown the roast on both sides. then add just enough water to cover the top of the roast and allow to boil all the way down to half inch of fluid in the bottom.
then add your onion in the left over juice with roast and allow them to cook till brown and clear. Now add more water again, covering top of roast by 3 inches over roast. add 1 envelope of beefy onion soup mix and let simmer for next 3 hours. check roast with a fork and twist if its tender it will come apart then add your potatoes and carrots cook till potatoes are a nice brown color.
take the brown gravey and mix it up in cool water like package says, then turn it into the roast water and stir till thickens... serve over mashed potatoes.