First, preheat your oven to 425F and line a baking sheet with parchment paper. Set aside. Then, add cauliflower florets and parsnips to a medium pot and cover with water. Bring up to a boil. Once boiling, season generously with kosher salt and reduce the heat to a more gentle boil, about medium-low, for 12 minutes or until very fork tender and almost falling apart.
1 lb cauliflower florets, 10 oz parsnips
Meanwhile, add walnuts to a food processor and pulse until finely chopped (you can do this by hand with a knife if you don't own a food processor). Add chopped walnuts to a bowl along with the panko breadcrumbs, lemon zest, dried thyme, garlic powder, kosher salt & black pepper, and stir to combine. Then, add in the oil and stir until evenly moistened.
½ cup raw walnuts, ⅓ cup panko breadcrumbs, ½ tsp lemon zest, ½ tsp dried thyme, ½ tsp garlic powder, ½ tsp kosher salt, ¼ tsp black pepper, 2 tbsp olive oil
Pat salmon filets dry with a paper towel, then add them skin side down to the parchment-lined baking sheet and brush dijon mustard over the top of each. Scatter walnut topping evenly over the salmon filets, pressing down to adhere. Transfer to the oven to bake for about 15 minutes, or until done through.**Cook time assumes that you are using salmon filets that are about 1.25-1.5" thick. For filets that are closer to 1-1.25", start with 13 minutes. 1 ½-2 tbsp dijon mustard, 4 5oz salmon filets
Meanwhile, add apple cider to a large, wide pan and bring up to a boil over medium-high heat. Then reduce heat to a simmer over medium-low for about 10 minutes until it has reduced significantly and is starting to lightly coat the back of a spoon. Then, whisk in the dijon mustard, lemon juice & kosher salt. Turn off the heat and whisk in the butter until melted and the sauce is glossy.
2 cups apple cider, 1 tbsp lemon juice, 1 tsp dijon mustard, 1 tbsp unsalted butter, kosher salt
Once the cauliflower and parsnips are fall-apart tender, drain off excess liquid and add back to the pot over medium heat for 2 minutes to dry them out further. Turn off the heat and add in the butter, milk and kosher salt, then use an immersion blender to blend until smooth, adding more milk as needed. Alternatively, you can transfer it all to a food processor and blend it that way.
⅓ cup milk, 2 tbsp unsalted butter, kosher salt
Serve walnut crusted salmon over a bed of cauliflower parsnip puree followed by a few spoonfuls of apple cider glaze over top. Enjoy!