Preheat the oven to 425°F.
Trim the asparagus ends and toss them with a little olive oil, salt, and pepper. Spread them on a baking sheet.
Roast the asparagus in the preheated oven for about 12-15 minutes until tender and slightly caramelized.
Meanwhile, steam or boil the cauliflower florets until they are very tender, approximately 8-10 minutes.
Drain the cauliflower and blend it with a teaspoon of butter, garlic powder, salt, and pepper until smooth. Stir in the lemon juice for brightness.
Season the salmon fillet with salt and pepper. Heat a non-stick skillet over medium-high heat and add a drizzle of olive oil.
Sear the salmon, skin-side down first if applicable, for about 4-5 minutes on each side until a crispy crust forms and the center is just opaque.
Plate the salmon alongside a serving of roasted asparagus and a generous scoop of cauliflower mash. Optionally, drizzle a little more lemon juice on the salmon for extra flavor.