In a large bowl, toss the beef cubes with the flour, salt, and black pepper until the meat is evenly coated. This flour coating will help thicken the stew's gravy later.

Heat the vegetable oil or butter in a large Dutch oven or heavy-bottomed pot over medium-high heat. Brown the coated beef in batches to avoid overcrowding, cooking for about 5 to 7 minutes per batch until a dark, flavorful crust forms on all sides.

Remove the browned beef to a plate, then add the chopped onion to the same pot. Cook for 3 to 4 minutes until the onion is softened and fragrant, using a wooden spoon to scrape up any browned bits from the bottom of the pot.

Return the beef to the pot and pour in the beef broth. Bring the mixture to a gentle boil, then reduce the heat to low, cover with a tight-fitting lid, and let it simmer for 45 minutes to begin tenderizing the meat.

Stir in the diced potatoes, sliced carrots, and rutabaga. Cover the pot again and continue to simmer for another 30 to 40 minutes, or until both the beef and the root vegetables are completely fork-tender.

If the brown gravy is too thin for your liking, leave the lid off for the final 10 minutes of simmering to let the liquid reduce and thicken. Taste the stew and adjust the seasoning with additional salt and pepper if needed.

Ladle the hot stew into deep, warm bowls and sprinkle with freshly chopped parsley. Serve immediately with a side of traditional Norwegian flatbread or thick crusty bread to scoop up the savory brown gravy.