Wash and dry all produce. Preheat oven to 450 degrees. Cut potatoes into 1-inch pieces. Pick fronds from dill and discard stems. Finely chop fronds until you have 1 TBSP. Finely chop parsley. Mince or grate garlic. Zest lemon until you have 1/2 tsp zest, then cut into wedges.

Place potatoes in a medium pot with a pinch of salt and enough water to cover by 2 inches. Bring to a boil and cook until potatoes are easily pierced by a fork, about 15 minutes. Drain, then return to pot.

Meanwhile, toss broccoli florets on a baking sheet with a drizzle of olive oil and a pinch of salt and pepper. Roast in oven until beginning to turn bright green, about 5 minutes (we’ll be adding more items to the sheet later).

In a small bowl, combine parsley, lemon zest, panko, half the garlic, a pinch of salt and pepper, and a drizzle of olive oil. Pat cod dry with a paper towel, then brush fillets with a drizzle of olive oil. Season all over with salt and pepper.

After broccoli has roasted 5 minutes, remove sheet from oven. Give broccoli a toss and push toward one side. Place cod on other side of sheet. Brush a thin layer of mustard onto tops of fillets, then press crust mixture into mustard. Return sheet to oven and cook until broccoli is tender and cod is cooked through and flakes easily, 8-10 minutes.

Add 1 TBSP butter, remaining garlic, and dill to pot with potatoes. Heat over medium heat and toss until butter is melted and garlic is fragrant, 1-2 minutes. Divide potatoes, broccoli, and cod between plates. Serve with lemon wedges on the side for squeezing over.