Spread the beef out in a single layer. Sprinkle generously with the kosher salt and black pepper. Let the meat rest for about 20 minutes.
In a large Dutch oven warm the oil over moderately high heat - just slightly above medium heat. When the oil is hot, place a portion of the meat in the pan and brown on all sides, about 5 to 6 minutes. Transfer the meat to a bowl and continue cooking until all the meat has been browned.
After all the meat is cooked, add the sliced onions to the pan and cook until they are tender and somewhat translucent, about 10 to 12 minutes.
Pour the wine into the stockpot with the onions, stirring to deglaze the bits left in the bottom of the pan.
Return the beef to the pan and add the beef broth, the tomato paste, the bay leaves, dried thyme, dried parsley and brown sugar. Bring the liquid to a boil over medium heat, then reduce to medium low, cover and simmer for about 1-½ to 2 hours or until the meat is tender.
Add the potatoes, haricots verts, carrots, mushrooms, corn and tomatoes. Stir in 1 tablespoon of the beef base. Cover and continue cooking on medium-low for 1 hour or until the vegetables are tender and cooked through. Check for seasoning, adding the additional kosher salt or pepper and the remaining concentrated beef base* if needed.
Blend the butter and flour together, making a smooth paste. Stir it into the stew to “tighten”the stock. Cook for another 10 to 15 minutes.