In a bowl, combine and mix all together the soy sauce, lemon juice, 3 tbsp. of olive oil, Worcestershire sauce and pepper. Then set aside.
Using a paper towel, pat the pot roast to dry. Then slice the pot roast into bite sized chunks.
Add the beef slices into the bowl with the marinade sauce, mix it all together. Cover and put it into the fridge and let this marinade for at least 1 hour or up to 12 hours maximum.
After marinating the beef, put the all purpose flour into the baking tray lined with foil. Then take out the beef slices using tongs and place them on the baking tray with flour.
Coat each beef slice with flour, then set aside. Also set aside the marinade sauce.
Using a medium size dutch oven, heat the 2 tbsp of oil over medium high heat. Then sear 1/3 of the beef slices until browned or for about 1 minute per side. Then transfer to a plate and repeat the procedure for the remaining beef slices.
Add the remaining oil, stir fry the onion and garlic for about 2 to 3 minutes or until the onions are softened. Add the beef stirring continuously for about 3 minutes.
Stir the marinade sauce, potatoes and beef broth into the mixture. Cover and bring to a boil, then reduce the heat to medium. Simmer for 40 minutes and stir it occasionally.
Uncover and continue to cook for an additional 10 minutes or until it's tender to your likeness. Stir occasionally.
Add a few raw onion rings on the top and cook for 2 minutes. Serve and enjoy the beef stew with steamed rice and roasted vegetables.