Trim off both ends of the celery stalks. With the “trough” of the celery stalk facing upward, use the tip of a knife to cut it lengthwise into 2 or 3 thin strips.
Of all the basic knife skills to learn, dicing celery is perhaps the easiest to master.
Gather the strips into a bundle. Turn the bundle so it’s horizontal on the cutting board. Holding the bundle with your left hand if you’re right-handed or your right hand if you’re left-handed, cut the bundle crosswise across into small cubes. The closer you make the cuts, the smaller the cubes will be.