Preheat the oven to 450°F. Spray a rimmed baking sheet with nonstick spray (you can line it with foil or parchment paper first for easier clean up).
Place the broccoli and potatoes on the baking sheet and drizzle with 2 tablespoons olive oil. Sprinkle over the garlic, red pepper flakes, and salt and pepper. Toss the mixture then spread it out on the baking sheet in an even single layer. Roast for 15 minutes.
While the vegetables are roasting, rub the pink side salmon fillets with the remaining tablespoon of olive oil. Sprinkle with salt and pepper. Remove the tray from the oven, and nestle the salmon in between the vegetables. Return the tray to the oven and roast for another 10 minutes, until the vegetables are crisp in spots and tender, and the salmon is cooked to your liking.
Divide amongst plates and serve with the lemon wedges, if desired.