It all starts with a layer
This leek, like many things in nature such as plants and geologic formations, is composed of layers. The view you see in this photo is a cross-section, clearly showing the layers. However, if you looked at the leek from the top down, you would see only the topmost layer. Pursuing this analogy a little further, leeks are a member of the onion family and often have some degree of transparency. If the topmost layer of the leek were partly transparent—or removed—you would begin to see the layers farther down the leek’s layer stack. This is pretty much the way layers work in Photoshop.
By the way, my wife was cooking soup ...