Preheat your oven to 400°F and line a baking sheet with parchment paper.
Toss the cubed sweet potatoes with half of the olive oil and a pinch of sea salt, then spread them in a single layer on the baking sheet.
Roast the sweet potatoes for 20 to 25 minutes until they are tender and slightly browned.
Season the salmon fillet with sea salt and black pepper on both sides.
Heat the remaining olive oil in a large non-stick skillet over medium-high heat.
Place the salmon in the skillet skin-side down and sear for 4 to 5 minutes until the skin is crispy, then flip and cook for another 3 minutes.
Remove the salmon from the pan and set aside to rest.
In the same skillet, add the minced garlic and sauté for 30 seconds until fragrant.
Add the fresh spinach to the skillet and toss constantly until just wilted.
Plate the seared salmon alongside the roasted sweet potatoes and sautéed spinach, finishing with a fresh squeeze of lemon juice over the fish.