Build the marinade: Put the chopped tomatoes, cucumber, peppers, garlic and scallions into a large bowl. Add the torn bread, the chopped basil stalks and 3 or 4 basil leaves, the sherry vinegar, the olive oil, salt and pepper. Mix everything with your hands, pressing down hard to squeeze the juices out of the vegetables.
Marinate and chill: Cover the bowl and refrigerate for at least 30 minutes — overnight is even better. Press the vegetables down one more time before you leave them so the juices keep breaking out and the bread starts to dissolve.
Blend silky smooth: Tip everything into a blender (work in batches if needed) and blitz for 2 to 3 minutes until completely smooth. If it is thicker than you like, blend in an extra glug of olive oil. Taste and adjust — it may need more vinegar or salt.
Chill it ice cold: Pour the gazpacho back into the bowl or a pitcher, cover, and chill for at least 2 hours until properly ice cold. Ramsay's trick: freeze a cup of the finished soup in ice cube trays and drop a few cubes into each bowl just before serving so it stays cold without watering down.
Make the griddled toasts: Brush the bread slices with olive oil on both sides. Cook in a hot griddle pan or skillet for 1 to 2 minutes per side until golden and crunchy. Sprinkle with flaky salt while warm.
Serve: Stir the gazpacho and taste once more — seasoning shifts when soup is very cold, so it may need another splash of vinegar. Serve ice cold, scattered with the remaining chopped basil leaves, a generous drizzle of olive oil, and the griddled toasts alongside.