Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper for easy cleanup.
Prepare the vegetables by trimming the tough, woody ends off the asparagus and slicing the red bell pepper into thin, uniform strips.
Place the salmon fillet in the center of the baking sheet and arrange the asparagus and bell peppers in a single layer around it.
Drizzle the extra virgin olive oil evenly over the salmon and the vegetables.
Whisk together the sea salt, black pepper, dried oregano, and garlic powder in a small bowl, then sprinkle the mixture over everything on the tray.
Toss the vegetables gently with tongs to ensure they are well-coated in the oil and spices, and press the seasoning into the top of the salmon.
Roast in the oven for 12 to 15 minutes, or until the salmon is opaque and flakes easily with a fork and the vegetables are tender-crisp.
While the salmon roasts, gently warm your pre-cooked brown rice in a small pan or the microwave.
Divide the rice onto a plate, top with the roasted salmon and vegetables, and finish with a bright squeeze of fresh lemon juice before serving.