In a small pot, over medium-low heat, add the vinegar and brown sugar, and whisk to combine. Cook and reduce until thick, about the consistency of maple syrup. Whisk in 2 tablespoons butter and season with salt and pepper, to taste. Serve drizzled over filet mignon and asparagus.
For Filet and Asparagus:
Slice the bottom 1 1/2 inches off the asparagus. Bring a large pot of water to a boil over medium heat. Add the asparagus and blanch for 1 minute. Remove from the water and shock in an ice bath. Transfer the asparagus from the ice bath to a sheet pan lined with a paper towel.
Take the filets out of the refrigerator 20 minutes before they are to be cooked so they can come to temperature.
Preheat oven to 300 degrees F.
Heat canola oil in a large heavy bottomed skilled over high heat. Season each filet liberally with salt and pepper. Sear the filets in the skillet until brown and crispy, about 2 minutes per side. Turn the heat to low and add the 4 tablespoons of butter, the garlic and fresh thyme. Using a spoon, baste the filets with the melted butter. Put the pan in the oven for 4 to 5 minutes for medium-rare or until the internal temperature reaches 130 to 135 degrees F on an instant-read thermometer. Let rest for 5 minutes before serving.
Heat a small amount of olive oil in a large skillet over medium heat. Add the asparagus, season with salt and pepper, to taste, and saute until heated through, about 2 minutes. Asparagus should be slightly tender but still have a little snap when you bite into them.
Preheat the oven to 400 degrees F.
To a large baking dish add the cauliflower, apple, and 3 tablespoons olive oil. Season with salt and pepper, to taste, and toss to coat. Roast in oven until brown on top, about 25 minutes, then add the vegetable stock and roast until tender, another 20 minutes.
Add the roasted cauliflower, apple and stock to a food processor and puree until smooth. Transfer to a metal bowl and put over a pot of simmering water to keep warm.
Turn oven down to 325 degrees F.
Heat some canola oil in a large heavy bottomed skilled over high heat. Season each fillet liberally with salt and pepper. Sear the fillets, skin side down, until brown and crispy, turn over and crisp the other side, about 2 to 3 minutes per side. Turn off the heat, add butter and, using a spoon, baste the fillets with the melted butter. Transfer to the oven to finish cooking, about 4 minutes.
Beurre Blanc Sauce:
Slice the green leaves off the leek and discard. Slice the stem into 1/4-inch thick rings. Put them into a large bowl filled with cold water and let soak for 5 minutes. Remove the leaks and drain on a plate lined with paper towels.
Heat the olive oil in a large skillet over medium heat. Add leeks and saute until soft, about 4 minutes. Deglaze the pan with white wine and add the vegetable stock. Reduce by half and then whisk in the cold butter. Serve over sea bass.
Using a rectangular plate lay a bed of 3 to 4 asparagus down on 1 side of the plate. Arrange a piece of filet mignon on top and drizzle with the balsamic reduction. On the other side of the plate put about a 1/4 cup of the cauliflower puree, top with a piece of sea bass and drizzle with the leek sauce. Repeat with remaining ingredients to make a total of 6 servings.