Guinness Beef Stew

0 Generously season all sides of your stewing steak pieces with salt and pepper.
1 In a heavy-bottomed ovenproof Dutch oven with a lid, heat the olive oil over medium-high heat and add the meat in batches, cooking for about 10 minutes, or until lightly browned. Scoop each batch onto a plate when done.
2 If the pan is too dry, add more oil as needed, then add the onions, celery, parsnip, and carrots. Cook for 5 minutes, until the vegetables are starting to soften. Sprinkle the flour and cook, stirring often, for 2 to 3 minutes.
3 Add the beer, stock, tomato paste, and mustard. Bring to a boil, stirring and scraping to dissolve all the browned bits on the bottom of the pan. 
4 Return the meat to the pan, along with the thyme and bay leaf.  Season with salt and pepper and cover with the lid. Turn the heat to low and simmer very gently for 2 hours.
5 Add the potatoes and continue simmering for 1 hour more, until the potatoes and meat are tender. Season with salt and black pepper and discard the bay leaf and thyme stems.
6 Serve hot. 
Oven Cooking Method
8 This stew can also be cooked in the oven at 325F for 2 hours before adding the potatoes.After you add the potatoes, continue to cook for 1 more hour, until everything is tender