Mix cream cheese and mineral water. Wash spring onion and radish and grate dry. Chop half of the spring onion very finely, cut the other half into thin rings. Slice the radishes very thinly.
Mix cream cheese and chopped spring onion and fill into a piping bag with a large star-shaped spout. Spray cream onto 5 crackers and garnish with radish slices and spring onion rings.