Creamy, starchy, salty, crunchy, cheesy -- here's plenty of proof that plain white can be every bit as thrilling to the taste buds as it is to the eyes.
Process fish, mayonnaise, lemon juice, and pepper in a food processor until smooth. Transfer to bowl; stir in 1/4 cup celery. Refrigerate, airtight, up to 3 days.
Just before serving, make sandwiches (1/4 cup salad in each). Trim crusts; cut in half lengthwise. Press some remaining celery against ends so it sticks (use a bit of mayo as "glue"). Place on tray, cover with a damp towel, and refrigerate until ready to serve, up to 1 hour.