Position a rack in the upper third of the oven and preheat to 425°F. Line the sheet pan with parchment if you like. Pat the salmon fillets dry with paper towels — dry fish sears and caramelizes better.

In a small bowl, whisk together the honey, soy sauce, minced garlic, rice vinegar, sesame oil, and red pepper flakes (if using). Set aside about 3 tablespoons of the glaze in a separate small dish for serving — the rest goes on the fish before roasting.

Toss the broccoli florets with 2 tablespoons of the olive oil, 1/2 teaspoon of the salt, and 1/4 teaspoon of the pepper directly on the sheet pan. Spread into a single layer with space between pieces — crowding steams instead of roasts. Roast for 10–12 minutes, until the edges start to char.

Push the broccoli to the edges of the pan. Rub the salmon fillets with the remaining 1 tablespoon olive oil and season with the remaining salt and pepper. Arrange skin-side down in the center of the pan. Brush generously with the larger portion of honey garlic glaze.

Return the pan to the oven and roast 10–12 minutes, until the salmon flakes easily with a fork and reads 145°F on an instant-read thermometer at its thickest point, and the broccoli is crisp-tender with charred edges.

Switch the oven to broil on high. Brush the salmon once more with glaze and broil 1–2 minutes, watching closely, until the glaze bubbles and caramelizes in spots. Rest 2 minutes, then shower with sesame seeds and green onions and serve with lemon wedges and the reserved glaze for drizzling.