Use a knife or mandoline to cut thin, circular slices of lemon. Make a single cut through the peel, then carefully remove the fruit and work your way around the lemon, freeing the peel from the fruit. Cut or peel off any remaining pith.
Wrap it around your finger, a pencil, a straw or simply around the peel itself in a spiral shape. Hold it together with your fingers or use a small but gentle clamp.
Advanced method
Hold the lemon in your non-dominant hand. In the other, place a sharp paring knife or vegetable peeler near the top of the lemon. You peel around the round part of the lemon, not from end to end.
Remove a thin, ¼ to ½ inch piece of lemon peel, carefully avoiding the bitter white pith. On a cutting board, cut off any rough edges if there are any, so you have a rectangular piece of peel.
Wrap it around your finger, a pencil, a straw or simply around the peel itself in a spiral shape. Hold it together with your fingers or use a small but gentle clamp. Hold it there for about 30 seconds. If it does not hold its shape when you unfurl it, wrap it up again and hold it for longer, until it holds its shape.
Notes
A traditional lemon twist is about ¼ inch thick. You can go thinner to ⅛ inch or up to to ½-inch thick, or even make some that are 1-inch thick.Check out these tips to make the most perfect citrus curls:
For the best flavor and aroma, use organic lemons. This is not something completely necessary to do, but I find that the peel on organic lemons tends to be better than conventional ones.
Don't press too hard when waiting for the curl to take shape or you could press the oils out of the peel and cause the peel to lose its shape. The oils add a nice flavor and aroma to a beverage, so you don't want to lose that!
Use different widths for different effects. Make thin strips if you need a lot of garnishes and don't have a lot of lemons. The thinner ones are really elegant too!