Preheat your oven to 400°F and line a large sheet pan with parchment paper for easy cleanup.
Slice the baby potatoes into halves or quarters so they are uniform in size. Slice the red bell peppers into thick strips.
Place the baby potatoes on the sheet pan, drizzle with 1 tablespoon of olive oil, and sprinkle with a pinch of salt and pepper. Roast for 15 minutes.
While the potatoes are roasting, whisk together the remaining 3 tablespoons of olive oil, lemon juice, lemon zest, dried oregano, garlic powder, and the remaining salt and pepper in a small bowl.
Remove the sheet pan from the oven. Move the potatoes to one side and add the cod fillets, broccoli florets, and bell pepper strips to the pan.
Drizzle the lemon-herb mixture evenly over the cod and the vegetables, using a brush or spoon to ensure the fish is well-coated.
Return the pan to the oven and roast for an additional 12 to 15 minutes, or until the cod is opaque and flakes easily with a fork.
Garnish the entire pan with freshly chopped parsley and serve immediately with extra lemon wedges if desired.