Soak the sliced onion in some ice water for 5 mins, this helps tame some of its heat. Once soaked, remove from the water and pat dry with kitchen paper.

Spread one slice of the bread with butter. Mix the Dijon, mayonnaise and honey with a pinch of salt and pepper in a small bowl. Spread across the inside of both slices of bread.

Sprinkle the tomato slices with salt and pepper. Layer up the sandwich with the ham, cheese, watercress, the onion and tomato. Lay the remaining slice of bread on top and slice in half.