Hankering for a midnight snack? Bet you haven’t considered Louis’ Lunch, which happens to be open just as late on weekend nights as Yorkside Pizza. Maybe the establishment isn’t on your radar because in a city famous for somewhat unfriendly customer service — as anyone who’s waited two hours only to be ignored by Sally’s waiters can attest — Louis’ Lunch has earned a similar reputation for refusing to provide any condiments to its customers.

But in fact the luncheonette is far from unwelcoming. As long as you can survive without ketchup or mustard, the miniature building with a red door on Crown Street is a quirky source of classic Elm City fare. Inside, the restaurant is just what one would expect from such an institution: wood-planked ceilings, a New Haven Landmark plaque, and benches and tables covered with years of carvings.

Don’t go for the atmosphere, though — the real New Haven pride is in the food. Louis’ Lunch doesn’t have a menu, but a few chalkboards and a little basic knowledge are sufficient to keep track of the limited options. One can order potato chips, local Foxon Park sodas, hot dogs, pie (baked by owner Jeff Lassen’s mother) or fantastic potato salad made with eggs and onions. According to their Website, Louis’ Lunch also sells tuna sandwiches on Fridays.

But the main attraction is of course the famous hamburger ($5), which original owner Louis Lassen is said to have invented himself in 1900 to satisfy a customer looking for lunch on the go. The burgers, as juicy and satisfying as you can imagine, are made fresh every day and served on toast instead of a bun in honor of the original. They are grilled vertically in the original 1898 broilers — a process which helps drain some of the fat from the burgers and uses flames on both sides to ensure even cooking. The burgers’ interiors are distinctively pink.

“We don’t like to make them well-done because we think it spoils the taste,” Jeff Lassen explained, but conceded that he will compromise in deference to the customer.

Not so, however, when it comes to toppings. Louis’ Lunch offers cheese, tomato and grilled onions — that’s it.

“Because we work really hard at giving you a superior product, we’d rather you taste it first,” said Lassen in defense of the long-standing tradition. “But I can see both sides,” he added considerately.

Lassen, who expressed concern about rising food prices and a desire not to pass the burden on to his customers, seems to genuinely care about his business and patrons. No wonder — as Louis’s great-grandson, he’s the fourth-generation proprietor of Louis’ Lunch. And the establishment seems to be doing better than ever under his ownership, serving up anywhere between 80 and 300 pounds of beef a day. This year’s Game weekend was their busiest ever, Lassen said.

Part of that success is likely due to increased publicity. Lassen said that Louis’ Lunch has been enjoying increased television exposure lately, including appearances on the Travel Channel, the Food Network, the History Channel and even Oprah.

Life for Louis’ Lunch hasn’t always been this easy, though. Lassen’s father Ken, the previous owner, nearly lost the restaurant in 1975, when the city wanted to build on the spot of its original location on the corner of George and Temple streets. Threatened with demolition, Ken Lassen eventually managed to get the entire building relocated by truck to its current address on Crown Street.

“Ken fought the city for survival for 15 years,” said Lassen. “Fortunately, we won out.”

As did the rest of New Haven.