The Vermonter is a cold sandwich organized around an apple, and the apple is the part that makes it Vermont rather than a generic deli turkey. Sliced green apple is not a garnish here: it is the structural counter to a sharp, dry Vermont cheddar and a soft cured meat, supplying the only crisp, wet, tart element in a build that would otherwise be three soft salty layers. Roasted turkey or sliced ham carries the protein, the cheddar carries the salt and the regional identity, and the apple is what keeps the whole thing from reading as one note. Take the apple out and it is a different, lesser sandwich.
The craft is in matching the components so none of them dominates. The cheddar is a firm, aged, slightly crumbly Vermont block, sliced thin enough to bend with the bread rather than shatter out of it, and sharp enough to stand against a sweet element without disappearing. The apple is cut thin and laid in a single even layer so it crunches without making the sandwich rock apart on the bite. Honey mustard does the binding and the seasoning at once: it glues the dry cheddar to the meat and threads a sweet, acidic line through every layer, which is why it is spread rather than pooled. The bread is a sturdy country loaf with enough chew to carry a cool, slightly wet load without going limp under the apple, and enough structure to be sliced thick and still hold.
The variations are mostly a swap of the protein or the spread within the same cold, sweet, sharp frame. Smoked turkey pushes it toward the savory end; maple mustard or a smear of apple butter leans it sweeter; a baguette or a croissant version trades the country crumb for crust or richness. Each of those keeps the cheddar-and-apple axis that defines it and changes one element around it, and each deserves its own article rather than being crowded in here.