The quantities here are enough for a few tapas. If you need to scale them up, you may not need to double the oil and seasoning. Instead of a kilner jar, you could use any suitable sealed container.
• 400g skinned mackerel fillets
• 15ml olive oil for searing
• 400ml olive oil for bottling
• 5 dried red chillies
• 1tsp peppercorns
• 1 rounded tsp salt
• 2tbs Moscatel vinegar
• Sprays of wild fennel
Cut the mackerel fillets into goujons. Heat the frying oil in a large non-stick pan until almost smoking. Stiffen the mackerel a few pieces at a time for about 15 seconds and reserve.
Boil the oil with the chillies, salt and vinegar.
Line a kilner jar with three or four sprays of fennel. Pack the mackerel into the jar and pour over the oil to fill it. Seal, cool and leave a day or so before eating.