The Green Line Gill has a diner vibe that’s mostly about hamburgers, which are as dissimilar to the fast-food varieties in the same way tart dill pickles are different from watery cucumbers — they’re related, but that’s where similarities end.

Before taking our order, owner/chef Bobby Couch described the basics of the “fried onion burger.” I was hooked as soon as he mentioned sauteed onions. This is what distinguishes Green Line from the rest of the pack. Those onions are incorporated into each patty on the flattop. Yet, that’s only the beginning.

Couch explained that everything is fresh, never frozen and locally sourced. And, it’s cooked to order, which means there’s a little longer wait

than at those fast-food venues.

The menu features six burger options, including a daily special, plus grilled cheese, a chicken sandwich, a Coney dog, Frito pie and macaroni and cheese.

We ordered the Deluxe ($7.50) and the Bacon Bleu ($7.50), and included a third-of-a-basket order of handcut fries ($2.50) with each. Later, we added the mac and cheese because we noticed a lot of people ordering it.

The Deluxe is a cheeseburger with pickles, sliced tomatoes, shredded lettuce, pickles, mayo, ketchup and mustard. It’s a straightforward version of an American classic: juicy and toothsome. It’s also worth noting that the bun did not disintegrate, which is often the case. Instead, it kept its shape while maintaining the perfect ratio of bread to meat and accoutrements.

The onions provide a savory and sweet element thanks to the caramelization that’s not lost when combined with everything else. This was also true with the Bacon Bleu, stacked high with crispy bacon, shredded lettuce and tomato. It’s drizzled with mayo, which blends nicely with the sharp, salty blue cheese. A bonus is the caramelized cheese that oozed down the side of the patty onto the grill. It’s much more than simply melted cheese; it takes on more flavor while adding crunchy texture.

The skins-on-fries are thinly cut, not greasy, and seasoned with the right amount of salt. They’re available in three basket serving sizes: third, half and full. It wasn’t clear what the actual amounts are in terms of ounces/ grams or other measurement, but the third was more than enough for two to share, although we didn’t.

The mac and cheese is velvety with lots of creamy cheese. This is the essence of comfort food. No wonder it was popular among those dining the same evening of our visit.

Other burger choices include a mushroom Swiss and a veggie. The daily special on our visit was a jalapeno with pepper jack and red chile. Red and green chiles are available as sides, as is slaw.

Couch is expanding The Green Line into the space next door, where he plans to offer barbecue. The smoker is already out front. (Once the new menu items have been in place a while, a review will follow.) For now, though, the small eatery with its black and white checkered floor, corrugated metal and red trim decor has its focus right where it should be: those fried onion burgers.