Ingredients :

• The Tomato — It’s the tomato or nothing. Pick a tomato that feels heavy for its size, which gives slightly when you press your thumb on it—not mushy, but not hard like a tennis ball either. In summer: Beefsteak or Marmande. Out of season, a Roma will do better than a supermarket round tomato picked too early. Avoid those that smell like plastic.
• White Sandwich Bread — Not a baguette, not whole grain. Thick white sandwich bread, a bit fluffy, which squashes pleasantly under finger pressure. Its role is to absorb the juice without disintegrating and not to steal the spotlight from the tomato. Harry’s or equivalent, thick slices if you have the choice.
• Mayonnaise — Real mayo. Hellmann’s if you’re in a hurry, homemade if you have 5 more minutes. It creates a barrier between the bread and the tomato juice—without it, the bread becomes a formless sponge in two minutes. Be generous, go all the way to the edges.
• Salt — Fleur de sel or coarse sea salt flakes. Not fine salt that disappears into the juice. Salt placed directly on the tomato slice draws out the juice and intensifies the flavor in 2-3 minutes. It’s a step, not just a seasoning.