Peel and cube the sweet potato, then boil in a pot of water until tender, approximately 10 to 12 minutes.
Preheat your oven to 400°F and line a baking sheet with parchment paper.
Trim the woody ends of the asparagus and place them on the baking sheet, lightly misting with a tiny amount of oil and a pinch of salt.
Roast the asparagus for 8 to 10 minutes until tender-crisp.
Pat the salmon fillet completely dry with a paper towel and season the flesh side with sea salt and black pepper.
Heat the avocado oil in a cast-iron skillet over medium-high heat until shimmering.
Place the salmon in the pan skin-side down and press gently with a spatula for 30 seconds to ensure even contact.
Sear the salmon for 4 minutes on the skin side, then flip carefully and cook for an additional 2 to 3 minutes until the internal temperature reaches 125°F for medium-rare.
Drain the sweet potatoes and mash them thoroughly with a fork or masher until smooth and creamy.
Spread the sweet potato mash on a plate, top with the roasted asparagus, and place the seared salmon on top.
Finish the dish with a fresh squeeze of lemon juice over the fish and vegetables.