Spring-Onion Egg Salad

In a medium bowl, stir the mayonnaise, mustard, salt, pepper, and pickle juice together, mixing well. Add the chopped eggs and green onion, folding them gently into the mayonnaise mixture. Spread each slice of bread on one side with the mayonnaise mixture, then place a lettuce leaf on each to cover it fully, using bits of the extra leaves if needed. Spread the egg mixture across the lettuce, dividing it evenly among the 4 slices. Using a sharp knife, cut each piece of bread twice on a diagonal to make 4 triangles. Sprinkle each with a few of the onion sprouts and flower petals.