Preheat your oven to 400°F (200°C) and line a small baking sheet with parchment paper for easy cleanup.
Peel and cube the sweet potato into half-inch pieces, then toss them on the baking sheet with 0.5 tsp of avocado oil and a pinch of sea salt.
Roast the sweet potatoes for 20-25 minutes, tossing halfway through, until they are tender and the edges are slightly caramelized.
While the potatoes roast, pat the salmon fillet completely dry with a paper towel and season both sides with the remaining sea salt and black pepper.
Heat the remaining 0.5 tsp of avocado oil in a high-quality non-stick or cast-iron skillet over medium-high heat until the oil is shimmering.
Place the salmon in the pan skin-side down and press firmly with a spatula for 10 seconds to prevent curling and ensure a crispy skin.
Sear the salmon for 4-5 minutes without moving it, then flip and cook for an additional 2-3 minutes until the internal temperature reaches your preferred doneness.
Remove the salmon from the pan to rest; in the same pan, add the minced garlic and fresh spinach, sautéing for 1-2 minutes until just wilted.
Plate the crispy salmon and roasted sweet potatoes alongside the garlicky spinach, finishing the dish with a fresh squeeze of lemon juice.