Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper.
Dice the Yukon gold potatoes into uniform 1/2-inch pieces to ensure they become perfectly tender and crispy.
Spread the potatoes on the baking sheet, drizzle with 0.5 tbsp olive oil, 0.25 tsp salt, and 0.125 tsp pepper, then roast for 15 minutes.
While the potatoes roast, pat the cod fillets dry with a paper towel to ensure a better sear and texture.
In a small bowl, whisk together the remaining 0.5 tbsp olive oil, lemon juice, minced garlic, and dried oregano.
Remove the baking sheet from the oven and slide the potatoes to one side to make room for the fish and asparagus.
Place the cod fillets and the trimmed asparagus onto the sheet, then brush the lemon-herb mixture over the top of the fish and vegetables.
Sprinkle the remaining salt and pepper over the cod and asparagus.
Return the sheet to the oven and bake for an additional 12-15 minutes until the cod is opaque and flakes easily with a fork.
Finish the dish with a generous sprinkle of fresh chopped parsley and serve immediately while the potatoes are hot and crunchy.