Sliced Egg Sandwich

Think of this like a deviled egg, unmixed, or deconstructed egg salad sandwich. The essentials here are a sliced just-about-hard-boiled egg (I stop at 9.5 minutes), a challah roll or slices (but brioche or a potato bread would work), a great fistful of arugula, and what I consider the perfect sandwich spread — some mayo, sharp dijon, coarse dijon, and prepared horseradish. A shot of hot sauce is not unwelcome; the mixture should be sharp. Between the egg and the arugula, I always have a thin layer of something and it’s different almost every time, usually leftover from another dish — caramelized onions, pickled shallots, shaved fennel I’d tossed in lemon juice and olive oil, cucumber, and here, some thinly-sliced pickles and celery — and every single one is perfect. I cannot choose a favorite and I won’t ask you to. Please have fun with it.

• 1/4 cup mayonnaise
• 1 tablespoon smooth dijon mustard
• 2 teaspoons wholegrain mustard
• 2 teaspoons prepared horseradish
• Salt and freshly-ground black pepper
• 2 soft challah, brioche, or potato rolls, split, or slices from a loaf
• Butter, for toasting
• 2 hard-boiled eggs, cold, peeled, and sliced
• Thinly sliced pickles, celery, pickled onions
• 2 cups fresh arugula, roughly torn