Albacore tuna is at its fattiest in the last month of the season, and most people buy it when it is leanest

Albacore tuna, or "bonito del norte" in Spanish, has a season running from May to the end of September. So we are now in its final month - and that is precisely when the fish is at its best, not its weakest. The fat in the flesh increases as the season goes on, so a September specimen is juicier and more flavourful than a June one. Most buyers think the opposite and buy at exactly the wrong time.

How it is caught, and why you can taste that

This fish is caught with hook and line, not with nets - selectively, one at a time. This is not about romance, it is about the state of the flesh: a fish pulled out on a hook has not been crushed in a net with thousands of others, so its structure stays intact. The weight does not exceed fifty kilograms.

Its route is strange. It is born in the Sargasso Sea, spends the winter around the Azores, Madeira and the Canary Islands, and in spring comes to the Cantabrian coast to feed on anchovies and sardines. What it eats there is why the flesh gets its flavour - a fish that eats other fish is not the same as a fish that eats whatever comes along.

Three things you can see at the counter

The skin must be glossy, smooth and moist. The flesh - firm and dense, an even reddish or dark red colour with no patches. The smell - of the sea, pleasant. If it smells sour or of ammonia, hand it back and walk away. This is not advice for gourmets, this is the basic check every grandmother at the market makes and the entire generation below her has forgotten to make.

The mistake everyone makes

They overcook it. Albacore dries out fast and then it is over - no sauce will bring it back. Take it out of the fridge a few minutes before it goes on the heat. If you are adding it to something cooked, it goes in last: it needs about three minutes and it is best if the heat left in the pot finishes the job, not the flame.

Otherwise it works on a griddle, on the grill, in the oven, in a stew, in a marinade, or raw - as tartare or carpaccio. It is rich in omega-3 fatty acids and good quality protein, if that is your argument.

The season closes at the end of September or the start of October. After that you wait until May.