Preheat your oven to 425°F (220°C). Line a baking sheet with parchment paper for easy cleanup.
In a large bowl, combine the broccoli florets with olive oil, salt, garlic powder, and onion powder. Toss until the broccoli is evenly coated.
Spread the broccoli in a single layer on the prepared baking sheet.
Roast in the preheated oven for 20-25 minutes, or until the broccoli is crispy and slightly browned, tossing halfway through for even cooking.
Remove from the oven and immediately sprinkle with nori flakes and sesame seeds, if using. Toss gently to combine.
Serve warm with fresh lemon wedges on the side for squeezing over the broccoli.