Pour a long blob of tempered chocolate onto parchment paper.
Use a clean hair comb or a special cake decorating comb to drag lines on both sides of the chocolate.
Use your finger to paint the outline of the leaf.
Cool until hardened (about 30 minutes in the refrigerator) and then peel off the parchment.
Notes
If you have tempered the chocolate properly, you can store your chocolate leaves at room temperature in an air-tight container.For a more realistic looking chocolate leaf, you can paint tempered chocolate onto the veiny side of real, green leaves. Make sure they are completely clean and dry and aren't poisonous (like poison ivy or poison oak).