Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Slice the baby potatoes into halves and chop the bell pepper and zucchini into bite-sized chunks.
Place the potatoes, broccoli, peppers, and zucchini on the baking sheet, then toss with 1 tablespoon of olive oil, sea salt, black pepper, and dried oregano.
Roast the vegetables in the oven for 10 minutes to give the potatoes a head start.
Remove the tray and move the vegetables to the edges to create space in the center.
Place the cod fillet in the center, drizzle with the remaining 0.5 tablespoon of olive oil, and top with minced garlic.
Return the tray to the oven and bake for 12 to 15 minutes, or until the fish is opaque and flakes easily with a fork.
Remove from the oven and immediately squeeze the fresh lemon juice over the fish and vegetables before serving.