Instructions

1. Position a rack in the center of the oven and preheat to 425°F. 
2. Use a paper towel to pat the salmon dry, then season lightly all over with salt. Set aside, uncovered and skin side down.
3. To a medium pot over medium-low heat, add the milk and 8 tablespoons of the butter and cook, stirring and scraping the bottom of the pot frequently, until the milk solids are deep golden brown and the butter is very fragrant, 8–10 minutes. Remove from the heat, carefully transfer the browned butter to a metal bowl, and place the bowl into a larger bowl filled with ice to chill while you prepare the sunchokes and salmon. (Alternatively, transfer the bowl of butter to the freezer.)
4. To a large pot of generously salted water, add the sunchokes and bring to a boil over high heat. Cook, stirring occasionally, until the sunchokes are tender when pierced with a fork, 20–30 minutes. Drain, then set aside until cool enough to handle.
5. Break the sunchokes into jagged, bite-size pieces, then toss with 2 tablespoons of the vegetable oil until thoroughly coated. Transfer to a large baking sheet and bake, stirring occasionally, until crispy and golden all over, about 40 minutes.
6. Meanwhile, cook the salmon: Pat the salmon dry again. To a large, deep, nonstick skillet over medium-high heat, add the remaining vegetable oil, swirling to coat the bottom of the skillet. When the oil begins to smoke, add the salmon, skin side down, and turn the heat to medium-low. Cook until the salmon skin begins to brown and crisp, 2–3 minutes, then pour off any excess oil but leave the salmon in the skillet. Add the garlic, thyme, and 2 tablespoons of the butter and cook, using a spoon to occasionally baste the salmon with the pan juices, until the flesh is nearly opaque and just flakes when poked with a fork, 2–4 minutes. (The butter should melt and turn light brown while you baste the salmon.) Using a thin spatula, turn the salmon over and continue cooking until very lightly browned, 20–30 seconds more, then transfer, skin side up, to a paper towel-lined plate.
7. Cut the remaining butter into small cubes. Retrieve the chilled browned butter and cut into small cubes as well. To a medium pot, add the stock, curry powder, and lemongrass and bring just to a simmer over medium-low heat, then turn the heat to low. Using an immersion blender or whisk, slowly add the butter and browned butter, a few cubes at a time, until all of the butter is incorporated and the sauce is smooth and emulsified. (Don’t walk away from the stove or let the sauce come up to a boil or the emulsion may split.) Remove from the heat, remove and discard the lemongrass, and season the sauce to taste with salt, liquid smoke (if desired), lemon juice, and white wine vinegar. Stir in the parsley and set aside.
8. Make the salad: In a medium bowl, whisk together the mustard and egg yolk, then whisk in the lemon juice, sherry vinegar, and sugar. While whisking vigorously, slowly drizzle in the olive oil, followed by the vegetable oil, until the dressing is smooth, glossy, and emulsified (you may not use all of the vegetable oil). Season to taste with salt and freshly ground black pepper. In a second medium bowl, toss the radicchio and other chicories with just enough vinaigrette to lightly coat. (Reserve any remaining vinaigrette for another use.)
9. To serve, spoon a generous pool of the butter sauce onto four medium plates. Divide the salmon and sunchokes among the plates, top each with some of the radicchio salad, and serve with additional butter sauce on the side.