Preheat your oven to 400°F and line a large sheet pan with parchment paper for easy cleanup.
Trim and halve the Brussels sprouts, then toss them directly on the pan with half of the olive oil, sea salt, and black pepper.
Spread the sprouts in a single layer and roast for 10 minutes to begin tenderizing and browning.
While the sprouts roast, whisk together the remaining olive oil, fresh lemon juice, lemon zest, minced garlic, and dried oregano in a small bowl.
Remove the pan from the oven, push the sprouts to the edges, and place the salmon fillet in the center.
Brush the lemon-herb mixture generously over the top of the salmon and season with an extra pinch of salt if desired.
Return the pan to the oven and roast for another 10-12 minutes until the salmon is opaque and flakes easily with a fork.
Divide the warm quinoa between plates and top with the roasted salmon and charred, crispy Brussels sprouts.