Welcome to O’Sardi’s!

For the new movie “Blue Moon,” starring Ethan Hawke as the famed Broadway lyricist Lorenz Hart, a replica of the iconic Theater District restaurant Sardi’s was built in a film studio in Dublin — 3,000 miles from West 44th Street.

“We have to build Sardi’s somewhere,” director Richard Linklater told The Post. “They’re not going to give us Sardi’s for a month.” 

Ultimately the crew jetted to the Emerald Isle.

“The historical challenge is very real,” Linklater added. “We redo all those pictures. You read every book. You get the actual designs, the architectural drawings. So it’s fun to do a very, very specific re-creation.”

Of course, structural changes were made to suit the unique needs of the film, which is set on March 9, 1943, the opening night of Rodgers and Hammerstein’s “Oklahoma!” 

The downstairs bar, where most of the movie’s witty action takes place while whiskey flows, is much smaller in real life. 

Hawke’s Hart, Bobby Cannavale’s bartender and Andrew Scott’s Richard Rodgers, who wrote “Pal Joey” and other shows with Hart before partnering with Oscar Hammerstein, needed room to spread out. 

And there are Easter eggs hidden in the newly created caricatures hanging on the wall. 

But the classic style and ambiance of the New York institution, which opened in its current location in 1927, are spot on.

Remarkably so, because Dublin production designer Susie Cullen has never step foot in Sardi’s before.

“I was sent videos of a walk-through,” Cullen told The Post. “As you walk in through the door and what you see when you look left, what you see when you look right.”

She added: “We changed reality and made it work.”

Cullen prioritized what she believed were the eatery’s important aspects: the amount of cartoons on display, the deep red and brown color tones and the abundance of dark-stained wood.

The film was made on a tight budget. So the designer borrowed wood flats from other projects.

And some 100 original caricatures were drawn by a local artist to look like the well-known portraits at Sardi’s.

But they’re not all of Broadway royalty of the day like Tallulah Bankhead and Ethel Barrymore.

“A few crew members appear among the caricatures,” Cullen said, including Linklater, “John Sloss, the producer, and his family, and one of the other producers, a couple of art directors.”

Another aspect of creating the of-a-different-era Sardi’s in the film is the performances. Hawke and Cannavale did hands-on research to nail the vibe.  

“Ethan and I live three blocks away from each other,” Cannavale told The Post. 

“Like the month before we went to Dublin, we went to Sardi’s a few times and we hung out. We’ve hung out there before, because we’ve had opening night parties there. I think we both have our caricatures up on the wall.” 

Then, on the night prior to flying to Dublin, Hawke told The Post, Tony winner Patti LuPone walked in and joined the pair for a drink.

“Patti LuPone was holding court and people were coming in and there was all kinds of Broadway gossip happening,” Hawke said. 

“And Bobby went behind the bar and asked the bartenders about different details about what it’s like to work there and how it would have changed.”

Actually, making “Blue Moon,” which is now in theaters, proved something of a homecoming for Cannavale, who currently stars in “Art” on Broadway with James Corden and Neil Patrick Harris.

“I worked in a lot of bars in New York City,” he said. “Not Sardi’s, but yeah, it did feel pretty authentic to the actual Sardi’s, for sure.”