My friend Cynthia has a family business, fashioning soaps with spring water, natural oils, herbs, flowers and fragrances. They come in all sorts of colors and aromas: almond milk; honey, wheat and yogurt; mixed berries; chocolate; kiwi; melon and cucumber. I've been using them for years. They look good enough to eat, but I wouldn't recommend that you do. They make great Christmas gifts.
She usually sells them on the streets of the Colonia Condesa in the morning and in Coyoacán in the afternoon. If you cannot find her, send her an email at email@example.com.