In a mixing bowl, add the sardines and the oil from the tin. Mash with fork and mix in the oil.
Add the carrot and spring onion and mix in, season with salt and pepper to taste if desired. (I use a mandolin with a julienne blade and chop after, resulting in a fine dice.)
Beat the egg in a small bowl and set that near you. Place a wonton skin on your work surface with a corner pointed towards you.
Place a teaspoon of the sardine mixture in the center of the skin, place a cube of cheese on top. Brush the 2 edges of the skin that are farthest away from you with some beaten egg.
Take the corner closest to you and fold away from you to the opposite corner and pat down the edge to seal the wonton. Set the wonton on a plate, there, you just made a wonton.
Repeat using the rest of the sardine mixture and wonton skins.
Heat oil in a pan for shallow frying, about ½ inch oil. When hot but not smoking, add some wontons and fry until golden brown on the bottom, then turn them over and fry the other side. Remove to paper towels to drain.
Serve and enjoy with dipping sauces of your choice.