"This delicious beef stew combines elements of a traditional American beef and barley stew with those of the classic French boeuf bourguignon. I created this for my husband, much to his delight. Guests have raved, too. This is a time-consuming recipe, but I don't think you'll be disappointed. Serve with boiled new potatoes if desired."
Place beef in a bowl; sprinkle with 1 teaspoon salt. Toss with flour to coat, shaking off excess flour.
Place bacon in a skillet and cook over medium-high heat, turning occasionally, until evenly browned, about 10 minutes. Transfer bacon to a large stock pot, reserving 2 tablespoons bacon fat in the skillet.
Place the floured beef cubes in the still-hot skillet; cook in batches until browned on all sides, 8 to 12 minutes. Transfer beef to the pot with the bacon. Combine the remaining 1 teaspoon salt, celery, chopped onion, carrot, garlic, and red pepper flakes in the skillet. Cook over medium-high heat until tender and lightly browned, 5 to 10 minutes. Transfer vegetables to the pot.
Remove the skillet from heat. Pour in red wine and cognac. Return the skillet to heat; light the liquid on fire with a long match or lighter to burn off the alcohol. Transfer the liquid to the pot once the flame has died out.
Heat the pot over medium-high heat. Stir in stewed tomatoes, beef broth, consomme, vinegar, tomato paste, thyme, bay leaves, and pepper. Bring to a boil. Reduce heat to low. Cover and simmer, stirring stew occasionally, until flavors combine, about 1 hour. Add barley; continue cooking until tender, about 1 hour more.
Place pearl onions in the previously used skillet with water to cover; boil until tender, about 5 minutes. Drain, reserving about 1 inch water in the skillet. Return onions to the skillet; sprinkle with sugar. Cook over high heat, stirring frequently, until water evaporates and onions are browned, 4 to 5 minutes. Add to the stew; add peas.
Melt butter in a separate skillet over medium-high heat. Add mushrooms; saute until golden brown, about 5 minutes. Add to the stew; remove and discard bay leaves.
Mix cornstarch and cold water together in a small bowl to make a slurry. Add slurry, 1 1/2 teaspoons at a time, to the stew, bringing to a boil after each addition until desired thickness is reached, 10 to 15 minutes. Garnish stew with parsley.