Preheat the convection oven to 400°F (200°C).
In a large bowl, toss halved baby potatoes with 1 tablespoon of olive oil, 0.25 teaspoon salt, and 0.25 teaspoon pepper.
Spread potatoes on a parchment-lined sheet pan and roast for 12 minutes to ensure internal starch gelatinization before adding faster-cooking components.
Remove the sheet pan and push potatoes to the perimeter. Place salmon fillets in the center.
Arrange broccoli florets and trimmed asparagus in the remaining open spaces.
In a small ramekin, whisk together the remaining olive oil, minced garlic, lemon juice, oregano, and remaining salt and pepper.
Drizzle the garlic-lemon mixture evenly over the salmon, broccoli, and asparagus.
Top each salmon fillet with a lemon slice.
Return the pan to the oven and roast for 12 to 15 minutes, or until the salmon reaches an internal temperature of 145°F (63°C) and vegetables are fork-tender.
Garnish the entire dish with fresh parsley and serve immediately.