Preheat your oven to 400°F and line a large rimmed sheet pan with parchment paper for easy cleanup and to prevent sticking.
Trim the woody ends off the asparagus and place the spears on the sheet pan along with the cherry tomatoes.
Pat the salmon fillet dry with a paper towel to ensure the best texture, then place it in the center of the pan surrounded by the vegetables.
In a small glass bowl, whisk together the olive oil, lemon juice, dried oregano, and garlic powder until the marinade is well emulsified.
Drizzle the lemon-herb mixture over the salmon and the vegetables, using your hands or a spatula to toss the veggies until they are evenly coated.
Season the entire pan evenly with the sea salt and freshly cracked black pepper for a balanced flavor profile.
Slide the pan into the oven and roast for 12 to 15 minutes, or until the salmon is opaque and flakes easily with a fork.
Remove from the oven and garnish with the freshly chopped parsley and additional lemon slices if desired before serving.