Step one

First Prepare the dye from onions skins - Fill your pot with water and about ten onions-worth of onion skins, and bring it to a boil for one hour, until you achieve your desired color. When the water becomes the color you like, strain the liquid. 

Step two

Mix the onion dye and the vinegar together and heat at medium temperature.

Step three

Then add the gelatin powder and glycerin and stir for a few minutes until the mixture thickens slightly.

Step four

Add the baking powder. The mixture will begin to react chemically and become fluffy.

Step five

Turn off the heat and carefully pour the mixture into a flat mould, and make sure to spread it out to let it dry.

Step six

Once it is ready the sheet can be carefully removed from the mold using a knife or scalpel.