Soak the salt cod for 36 hours in cold water, changing every so often. Drain and cut into 2cm chunks
Put the potatoes in a pan of cold salted water, bring to the boil then simmer for 15 minutes until tender but not broken down. Drain well.
Meanwhile, cover the salt cod with cold water and bring to a rolling boil then drain, reserving 175ml of the cooking water. Remove the skin and flake up the fish.
Heat the oil and garlic together over a low heat for a minute until aromatic then then stir in the flour and cook for a minute more. Gradually add the cooking water, stirring till you have a smooth thick sauce.
Fold in the olives and tip into a stand mixer with a paddle attachment. Add the cod and potatoes and beat until combined and most of the cod and potatoes have broken down but it’s not yet smooth then beat in the egg. You can do this vigorously with a wood
Heat the oil in a deep sided saucepan to 180c. Use two dessert spoons to scoop and shape spoonfuls of the bunuelos mixture together, making sure you press it together well, drop them into the hot oil a few at a time and cook for 2-3 minutes until golden
Drain on kitchen paper and repeat with the rest of mixture. Serve hot with the alioli to dunk them in.

Alioli

Make the alioli. Whisk the yolks with the vinegar and a good pinch of sea salt and ground white pepper.
Steep the saffron in the water for a minute then add to the egg yolks with the garlic. Gradually whisk in the oils until you have. Thick glossy, vibrant yellow alioli. Add lemon juice to taste.