All you do is dice two stalks of celery.
In a mason jar, mix 1/4 cup white wine vinegar (or plain white vinegar), 1/4 cup water, 2 teaspoons salt, and 1 1/2 teaspoons sugar. Shake until salt and sugar are dissolved.
I did put them in egg salad and it was delicious. Best egg salad I've ever had. Especially with rosemary flatbread.