Put some cooking oil in the bottom of a stockpot or large saucepan (one with a lid) and heat. Once the oil is hot add the pot roast. Season the chuck roast with plenty of salt and pepper. Be sure to brown well on all sides and edges as this will help keep in the juices. Once the meat has browned nicely add the onions & garlic.
Sprinkle meat with enough salt & pepper to your desired taste on all sides. Once onions have cleared slightly, add the remaining ingredients. Stir to mix all and just taste the liquid. If it does not taste sweet enough for you add more brown sugar.
Cover with a lid and turn heat down to medium on a propane stove and 8 on an electric. Let cook for 3- 3 1/2 hours or until meat is no longer pink inside. Be sure that you turn the meat every 15 - 20 minutes and stir the sauce over the meat and around it to avoid it sticking. When finished cooking the meat will be very tender and you will have a thick but sweet chunky gravy to serve with your roast beef.