Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper.
Pat the cod fillet dry with a paper towel on both sides to ensure the herb topping adheres properly.
In a small mixing bowl, whisk together half of the olive oil, the lemon juice, lemon zest, minced garlic, and dried oregano.
Place the cod fillet, asparagus spears, and cherry tomatoes onto the prepared baking sheet in a single layer.
Drizzle the remaining olive oil over the asparagus and tomatoes, tossing gently to coat.
Brush the lemon-herb mixture evenly over the top of the cod fillet and season the entire tray with sea salt and black pepper.
Bake for 12 to 15 minutes, or until the cod is opaque throughout and flakes easily with a fork.
Transfer the roasted vegetables and fish to a plate and serve immediately over the warm cooked quinoa.