Preheat your oven to 400°F and line a small baking sheet with parchment paper for easy cleanup.
Peel the sweet potato and cut it into uniform 1/2-inch cubes to ensure even roasting.
In a bowl, toss the sweet potato cubes with 0.5 tsp of olive oil and half of the sea salt, black pepper, and garlic powder.
Spread the potatoes on the baking sheet and roast for 20-25 minutes, flipping halfway through, until they are tender and golden brown.
While the potatoes roast, pat the salmon fillet dry with a paper towel and season both sides with the remaining salt, pepper, and garlic powder.
Heat the remaining 1 tsp of olive oil in a non-stick skillet over medium-high heat until shimmering.
Place the salmon in the pan skin-side up and sear for 4 minutes, then flip and cook for another 3-4 minutes until the fish is opaque and flakes easily.
In a small bowl, toss the arugula with the lemon juice and serve it alongside the seared salmon and roasted sweet potatoes.