Preheat oven to 400°F and line a baking sheet with parchment paper.
Peel and cube the sweet potato into 1/2-inch pieces, then toss with half of the olive oil, salt, and pepper.
Spread the potatoes on the baking sheet and roast for 25-30 minutes until tender and golden.
Pat the salmon fillet dry and season both sides with salt and pepper.
Heat the remaining olive oil in a non-stick skillet over medium-high heat.
Place the salmon skin-side up in the pan and sear for 4-5 minutes until a golden crust forms.
Flip the salmon and cook for another 3-4 minutes until cooked through, then remove from the pan.
In the same skillet, add the minced garlic and sauté for 30 seconds until fragrant.
Add the fresh spinach and cook until just wilted, then stir in the lemon juice.
Serve the seared salmon alongside the roasted sweet potatoes and garlic spinach.