Preheat the oven to 350⁰F.
In a small saucepan, bring the red wine and veal stock to a boil and reduce by ¾.
In a medium sauté pan set over medium heat, warm a few tablespoons of the olive oil and add 1 T of the butter. Add the red pearl onion, carrot, salsify, and mushrooms. Season with salt and cook on the stovetop, stirring, for about 5 minutes. Transfer to the oven and continue roasting for 20 minutes, tossing occasionally to ensure even cooking. Keep warm on the side.
Meanwhile, set a saucepan over medium heat and warm a tablespoon of olive oil. Add ¼ of the minced shallots and cook until translucent. Add the chopped parsnip and cook for 6 minutes, stirring occasionally. Add the milk, season with salt, bring to a simmer, and continue cooking another 10 minutes, or until the parsnip pieces are soft. Transfer to a blender and puree until smooth. Transfer the puree back to the saucepan and keep warm on the side.
In a large sauté pan set over medium high heat, warm 3 T of olive oil. Season the bison steaks on all sides with salt and freshly ground black pepper. Sear for 2 minutes on each side, then add 1 T of the butter, garlic, and thyme. Spoon the foamy butter over the steaks for 1 minute each side, and then remove them from pan to a resting rack. In the pan, sauté the remaining shallots until translucent, and add the reduced red wine and veal stock, along with the red wine vinegar, bring to a boil, then remove from the heat. Whisk in the remaining butter, remove the spring of thyme and garlic, and season to taste.
Dress the plates with a swipe of parsnip puree, the roasted vegetables and the bison steaks. Generously spoon the sauce over the steaks and garnish with the parsley leaves.