If you can’t find Imperial Stout you can substitute Guinness in this warming stew. Slideshow: More Russian Recipes
In a large bowl, toss the beef with the flour, 1 teaspoon salt and 1/2 teaspoon pepper.
In a large heavy pot, heat the oil over medium high heat until hot. Brown the beef, in batches, turning, 5 to 7 minutes per batch. Transfer the beef to a bowl as browned.
Pour off all but 2 tablespoons of fat from the pot, then stir in the onion and garlic and cook, stirring occasionally, until golden, about 6 minutes. Stir in the potatoes, stock, stout, Worcestershire and the beef with any accumulated juices. Simmer the stew, covered, until the meat is very tender, about 3 hours. Season with salt and pepper to taste, then serve sprinkled with the parsley leaves.