Start by washing and halving the baby potatoes so they cook evenly. Toss them with olive oil, salt, and pepper until well coated. Spread them out on a baking tray in a single layer for even roasting.
Place the tray in a preheated oven at 200°C (400°F). Roast for about 25–30 minutes until they turn golden and crispy on the outside. Flip them halfway through for even browning.
In a bowl, combine chopped parsley, capers, minced garlic, anchovies, mustard, and olive oil. Add lemon zest and juice, then mix until well combined. The sauce should be slightly chunky but well blended.
Pat the cod fillets dry with paper towels to remove excess moisture. Season both sides with salt, pepper, and a little lemon zest. This helps the fish develop a better texture while cooking.
Heat olive oil in a non-stick pan over medium heat. Cook the cod for about 3–4 minutes on each side until it turns opaque and flakes easily. Avoid overcooking to keep it tender.
Once everything is ready, plate the roasted potatoes and place the cod fillet on top. Spoon the salsa verde generously over the fish. Serve immediately while everything is warm and fresh