Porto-style salt cod with potatoes (Bacalhau à Gomes de Sá)

1. Soak the dried salt cod in cold water for 24-48 hours (changing the water 3-4 times); bring the milk to the boil, pour it over the fish and leave covered for 1 hour, then remove the skin and bones and flake the flesh into large pieces.

2. Boil the potatoes in their skins in salted water for 20-25 minutes until tender, peel and cut into slices about 1 cm thick; meanwhile hard-boil the eggs for 10 minutes and cut into wedges.

3. In a large frying pan, cook the thinly sliced onions and sliced garlic slowly in the olive oil for 10-12 minutes until golden and sweet.

4. Add the cod and potatoes, season with pepper and toss gently so the potatoes don't break up.

5. Transfer everything to an oiled earthenware or glass dish and bake at 200 °C for 15-20 minutes until lightly browned on top.

6. Serve garnished with the egg wedges, black olives and chopped parsley.

Tip: Resting the fish in milk was the secret of José Luís Gomes de Sá, a 19th-century Porto merchant: it makes the flesh soft, juicy and slightly sweet – don't skip this step.