“A few years back I took the patty melt off the menu.”

There is an apologetic tone to Jim Culcasi’s words as he recalls the moment. But time has passed, and he’s willing to confess his culinary misdeed. His pitch raises as if to emphasize the reaction of Rosine’s regulars.

“Oh my god,” he says.

Melts are simple sandwiches – essentially roadside diner fare from a different time, reminiscent of joints pouring coffee without name or lineage. And yet their nostalgic tug is firm enough to defy modern fusion.

The patty melt, for example, is nothing more than a burger topped with grilled onions and cheese – most often Swiss – between slices of toasted rye bread. There is no ciabatta, no avocado.

“There are no other gimmicks, nothing else between you and the patty,” explains Matt Grebing, owner of From Scratch in Carmel’s Barnyard. “The quality of the meat has to be top notch.”

Grebing’s team grinds the burger in-house from a selection of brisket and chuck in order to portion the fat. At Rosine’s in downtown Monterey, that figure is 80/20.

The sandwich simply makes sense. In its true-to-form presentation at RG Burgers in Carmel’s Crossroads, the sturdy earthiness of rye favors the brawny swagger of beef while the bite of caraway mimics that of a pickle, just without the jarring intensity. Swiss drapes its creamy tang on the palate, complementing the bread. Grilling the onions softens their pungent blow, nudging the meat with a hoarse sweetness. It’s just downright satisfying.

Rosine’s, From Scratch and RG Burgers are three Monterey County restaurants serving both popular melts, patty and tuna – the latter just a basic albacore tuna salad on bread, grilled with cheddar or American cheese.

“We’ve had it on the menu since we opened,” Culcasi says. “Sometimes when I walk through the kitchen I grab a scoop of it.”

Sure, the restaurants prefer sourdough and fresh tuna. But the sandwich owes its prominence in American culture to convenience, cost and 20th century innovation. Or, to put it another way, canned tuna, presliced bread and mayonnaise from a jar – all of which came available in time to meet the demands of factory lunch breaks and the Baby Boom.

Of course, it doesn’t need to be so basic. Rosine’s, for instance, uses line-caught albacore and griddles the bread to an inviting golden-brown.

There is a dubious tale cited by many to explain the origin of the tuna melt. Sandwiches of tuna salad already existed – Spain’s tuna bocadillo and the pan bagnat popular in France are early examples. But melted cheese came accidentally, at least according to legend.

As the story goes, neither the lunch counter cook nor the line of diners facing the flattop at a South Carolina Woolworth’s noticed when a bowl of tuna salad toppled toward the grill, somehow landing squarely on a grilled cheese sandwich.

That supposedly happened in the 1960s. Or the late ’50s. A Los Angeles restaurateur vigorously claims the patty melt, said to have been created sometime between 1940 and 1959.

However, since the first cheeseburger was served at either a Pasadena sandwich shop in 1924 or one in Louisville a decade later (or the Denver establishment that tried to trademark the word in 1935) – and since early burgers were likely served on bread rather than buns – it would seem the patty melt is part of the cheeseburger family.

There are other melts, such as turkey or ham. Cannery Row Deli offers a roast beef melt. Duffy’s Tavern in Monterey lists a veggie melt. The patty melt is an anomaly in the melt lineup – the only version where the protein involved is cooked just before plating. So just what defines a melt?

Food writers have stumbled over the answer for some decades. A common attempt explains the melt as a sandwich of meat – any kind – with melted cheese on toasted bread slices.

But what of the Reuben – or the many other sandwiches featuring melted cheese? Culcasi suggests that the bread is an important point of distinction. A true melt resides on sliced bread. But there is more to the melt.

“I would say it’s the idea – the cheese and meat becoming one, in holy matrimony,” Grebing says.