Preheat the oven to 350 F.

Sear the meat. Heat the oil in a Dutch oven over medium-high heat. Pat the meat cubes dry and season well with salt and pepper. Once the oil is heated, place the beef cubes in a single layer and sear until browned on both sides. You might need to perform this in batches. Remove the steak from the pan and place on a platter.

Make a herb bundle. Tie the rosemary and thyme sprigs together with kitchen thread, then leave away.

Saute vegetables. Reduce the heat to medium-low and add the butter. When the butter has melted, add the onions and leeks and toss to coat with the fat. Cook for 3-4 minutes, stirring periodically, until the vegetables have softened. Add the garlic and simmer for another minute.

Prepare the braising liquid. Stir in the tomato paste, dijon, and beef bouillon paste until the vegetables are well covered. Sprinkle in the flour and cook for another 2-3 minutes, stirring often. Pour in the wine, stir thoroughly, and bring to a simmer. Scrape any browned chunks from the bottom of the saucepan. Stir in the beef broth, followed by the bay leaves and herb bundle.

Braise. Return the meat to the saucepan with any juices that have collected on the platter. Cover and place in the oven for 2 hours.

Make horseradish sauce. In a small bowl, combine all of the ingredients and whisk until smooth. Season to taste with salt and pepper. Refrigerate until ready to serve.

Add the vegetables. Remove the steak from the oven and combine with the potatoes, carrots, parsnips, and turnips. Cover and return to the oven for another hour or two, until the meat is really soft. Remove from the oven and let the beef stew to rest for 30 minutes, covered.

Serve. Season the stew to taste, adding salt and pepper as required. Serve warm, topped with horseradish cream sauce.