Bring plenty of water with 1 tablespoon of salt and the vinegar to a boil in a saucepan.
Cut the crust off the toast. You can also cut shapes from the toast, e.g. a heart, a circle or a beetle shape. Then toast the toast in the toaster or in a pan with a little butter.
Gently beat the egg in a ladle or cup. The egg yolk must remain intact. Now carefully slide the egg into the boiling water and cook for 3-4 minutes. Then carefully remove the egg from the water, let it drain slightly, place on the toast slice, sprinkle with the chives and add a little salt. The slice of cheese is placed on top. I like to use sandwich slices that melt nicely in the oven.
Put the whole thing on a saucer in the preheated oven at about 200 ° and bake (about 5 minutes). I try to keep the baking time as short as possible so that the egg doesn`t dry out. Depending on the size of the egg, you get a creamy consistency at the times given.
Take the egg out of the oven (careful, the saucer is very hot) and, if you want, garnish with chives, ketchup and Worcester sauce.