Preheat the oven to 425°F. Line a baking sheet with parchment paper.
Wash and trim the asparagus. Toss it with 2 teaspoons of olive oil, salt, and pepper. Spread evenly on the baking sheet.
Roast the asparagus in the oven for 12-15 minutes until tender and slightly crispy at the tips.
Meanwhile, steam or boil the cauliflower florets until very tender, about 8-10 minutes.
In a small bowl, combine the steamed cauliflower with 1 teaspoon of olive oil, 1/4 cup Greek yogurt, salt, and pepper. Use a blender or immersion mixer to create a smooth mash. Adjust seasoning with lemon juice, salt, and pepper.
Pat the 6 oz salmon fillet dry and season both sides with salt and pepper.
Heat a non-stick skillet over medium-high heat. Once hot, add the salmon skin-side down (if skin is on) and sear for about 3-4 minutes until a crisp crust forms.
Flip the salmon and cook for an additional 3-4 minutes or until desired doneness is reached.
Plate the seared salmon alongside a serving of roasted asparagus and a generous scoop of cauliflower mash. Drizzle a little extra lemon juice over the top to brighten the flavors.