Cucumber and Watercress Sandwiches

• 1 bunch watercress, bottom of stems removed, finely chopped
• Salt and black pepper
• 4 tablespoons

Season the watercress with salt and pepper to taste. Using a food processor, an electric mixer, or by hand, cream the butter and add the mayonnaise and lemon zest. Spread the mayonnaise butter on all the bread slices, sprinkle half of them with watercress, and cover the watercress with some cucumber slices. Cover with the remaining slices of bread. Trim the crusts and cut each sandwich into 4 t