1. Preheat oven to 200°C. Boil the baby potatoes in salted water for 15–18 mins until tender. Drain and halve.
2. Cut the broccoli into florets and place on a baking tray. Drizzle with olive oil, salt and pepper. Roast 15–18 mins.
3. Mix mayonnaise with sour cream, a crushed garlic clove, lemon zest and juice. Season. Fold in the warm potatoes. Set aside.
4. Season the basa fillets. In the last 12 mins of broccoli cooking, push the veg to one side and lay the fish on the tray. Bake until fish flakes easily.
5. Serve fish alongside broccoli and the warm potato salad, sprinkled with fresh dill.