Peel and cube the sweet potato, then steam or boil until fork-tender, approximately 12 minutes.
Drain the sweet potato and mash thoroughly until smooth, adding a splash of hot water if needed for consistency.
Pat the salmon fillet completely dry with a paper towel and season with sea salt and black pepper.
Heat half of the olive oil in a stainless steel or cast iron skillet over medium-high heat.
Place the salmon in the pan and sear for 4 to 5 minutes until a golden crust forms, then flip and cook for another 3 minutes.
Remove the salmon from the pan and lower the heat to medium, adding the remaining olive oil and minced garlic.
Sauté the garlic for 30 seconds until fragrant, then toss in the fresh spinach.
Cook the spinach for 1 to 2 minutes until just wilted and bright green.
Plate the sweet potato mash, top with the garlic spinach and seared salmon, and finish with a squeeze of fresh lemon juice.