 Hard-boiled and chopped, you know, they're the protein component and base of the salad. You can't have egg salad without eggs. You got to chop those up real good. You're going to need mayonnaise because it adds creaminess and binds the salad together. Dijon mustard for a tangy depth and sharpness. Fresh lemon juice. And, you know, some people use white wine vinegar instead.