Some things don't so much need a recipe as they need good ingredients and a bit of common sense. The summer tuna sandwich that Spanish Olympic canoeist Saul Craviotto keeps sharing on his networks is exactly that - a few ingredients, plenty of flavour and zero complications. And, as he puts it himself, “a sandwich that never lets you down”.

It starts with good bread - crusty, with a hard crust and a firm centre that can carry the juicy fillings without falling apart. The bread is toasted in a pan with a few drops of olive oil to get a crisp surface and a toasted taste. Nothing new so far, but this is exactly where most people go wrong: soft bread under a juicy filling is a disaster waiting to happen.

The trick with the mayo

Craviotto makes homemade mayonnaise - and adds one step that many chefs use but home cooks rarely do: part of the oil from the tuna can goes straight into the emulsion. The result is a mayo with a deeper, more of-the-sea flavour that ties the whole sandwich into one. A small thing that changes the story.

On the toasted bread goes a generous spoonful of mayo, then: chunky pieces of quality tuna in olive oil, three roasted piquillo red peppers, four anchovy fillets and a few hot peppers that give just enough heat to wake up the other flavours. “Few ingredients, plenty of flavour and zero complications,” the canoeist writes. Hard to disagree.

A few rules for the perfect sandwich

Drain everything well - the tuna, the anchovies and the peppers must be properly drained, or the bread goes soggy. In simple recipes every ingredient counts, so the quality of the tuna, the peppers and the anchovies genuinely makes the difference. And most important: make it right before you eat it, to keep the crunch. A summer meal with no stove, that looks and tastes like you tried a lot harder than you actually did.