For a great sandwich, you need plenty of crunch and a good allotment of flavor and texture contrasts. Here, the tender, tasty lamb meat contrasts with the toasted bread and the crunchy, moist celery root salad. It’s important to place a lettuce leaf on either side of the lamb and celery root salad to keep the bread from getting soggy. Serve these sandwiches with some crispy gherkins and a glass of good ale.
Rub the bread slices lightly with the garlic and season moderately with salt and pepper, then toast them to your liking. (The best way to do this is on an outdoor charcoal grill; otherwise, do it in the oven at 350 degrees or on a griddle pan.)
Place the mayonnaise, celery root, tarragon, chives, and shallots in a bowl. Add the lemon juice, toss well to combine, then season to taste with salt and pepper. Make sandwiches layered as follows: 1 slice of bread, 1 leaf of lettuce, a portion of lamb, a portion of celery root salad, another leaf of lettuce, and a second slice of bread. Any excess salad can be served on the side or refrigerated for up to 2 days.