Preheat oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Chop the zucchini into half-moons, slice the bell pepper into strips, and trim the woody ends off the asparagus.
Place the vegetables on one side of the baking sheet, drizzle with 1 tablespoon of olive oil, and sprinkle with half of the oregano, garlic powder, salt, and pepper.
Toss the vegetables to coat evenly and spread them out in a single layer.
Pat the cod fillet dry with a paper towel and place it on the other side of the baking sheet.
Drizzle the fish with the remaining olive oil and lemon juice, then season with the remaining herbs and spices.
Bake for 12-15 minutes, or until the fish is opaque and flakes easily with a fork and the vegetables are tender.
Garnish with fresh chopped parsley before serving.