My friend Barbara Wagner gulped when the rib-eye cut she and her husband recently ordered medium-rare at Wolfgang’s on East 54th Street came to the table.

“We gasped. The outside was seared — it looked like a normal steak — but when we cut into it, it was practically raw,” says Wagner, a real estate publicist. “So we sent it back.” It was refired to perfection and she said she’ll go back to Wolfgang’s.

But chew on this, steak lovers: Your medium-rare cut is getting rarer, in both senses of the word.

A few days after Wagner’s experience, I ordered a boneless rib-eye medium-rare at Del Frisco’s Double Eagle Steakhouse in Midtown. What I got wasn’t remotely the medium-rare ideal of red at the center fading to pink around it, but the near-purple hue known as “blue rare.”

Both incidents reflected the new, medium-rare confusion. While getting an underdone steak has been a possibility for decades, what’s really given the phenomenon traction is that chefs are under bottom-line pressure to reduce throwaways that occur when customers say a steak is too well-done. An under-cooked steak, on the other hand, can always be salvaged with a touch more fire as my friend’s was.

Most chefs regard beef cooked to medium-rare — with an internal temperature of 130 degrees off the grill and 135 degrees after resting — as the best way to bring out flavor and retain moisture in tender cuts such as rib-eye and top loin. Unlike rare, medium-rare allows time for the outside to caramelize and develop a sear.

It “maintains the most flavor and it keeps the juice in the meat,” says Laurent Tourondel, the founder of the BLT Steak chain who’s now a partner in Brasserie Ruhlmann and L’Amico.

At Porter House New York in Midtown, executive chef and co-owner Michael Lomonaco says more than 60 percent of his customers order medium-rare.

Yet, the “medium-rare” rib-eye that I had at salt-spewing Salt Bae’s Nusr-Et was so red end-to-end, it resembled a bloody nose. Similar cuts that I braved in the last week, at STK in Midtown and at Delmonico’s in FiDi, were nearly as rare. Only Bowery Meat Company nailed medium-rare as I expect it, although Porter House New York’s slightly underdone, chili-rubbed rib-eye had the best overall flavor and char.

Mark Pastore, president of distributor Pat LaFrieda Meat Purveyors, which sells to scores of New York restaurants, says he first noticed the undercooking trend about a year ago.

“The norm has become [for customers expecting medium-rare] to order by a new term, medium-rare-plus, because people found their steaks were arriving undercooked — like rare-plus,” Pastore said.

I now ask for medium-rare-plus to prevent getting steak too raw and tough to chew. Even Bowery Meat executive chef Josh Capon says he now orders medium-rare-plus, rather than medium-rare, for himself when he’s out, because “most steakhouses are undercooking.”

Restaurateur Stephen Hanson says it’s mainly about money. Every cent counts when eateries are under unprecedented strain from high rents, high labor costs and brutal competition.

“If a customer says their steak is overcooked, it can only be thrown out,” says Hanson, the owner of Henry at Life Hotel who previously ran four steakhouses under the BR Guest banner, including the Strip House chain. So kitchens err on the rare side, knowing the dish can always be rescued with a minute or two more heat.

Tony Fortuna, owner of the always-buzzing TBar Steak & Lounge says he spends $34 to buy a 24-ounce, dry-aged cut of rib-eye, and, if one customer finds their steak overcooked, “we lose money on the whole table.”

Rising beef prices are also driving the cost.

“Right now I’m buying choice rib-eye [from ranches such as Creekstone Farms] for around $8 a pound,” says Pastore. “It was $6 two years ago.” Prime, the highest grade, now costs him “around $9.50 a pound, versus $8 two years ago.”

Adding to the issue is the fact that many chefs have dispensed with using meat thermometers and just go by feel, says Fortuna, who keeps a close eye on his steaks’ outer char as well as on their inner moisture.

“[Using a thermometer] creates a hole, juice comes out and the meat gets dry,” says Fortuna.

Then there’s the fad factor. Some chefs are swayed to undercook because rawness and near-rawness is seen as somehow superior.

“Overcooking steak is regarded [by some] as a greater moral and aesthetic sin than undercooking it,” Mark Schatzker, author of “Steak: One Man’s Search for the World’s Tastiest Piece of Beef,” tells The Post. “A rare steak is edgy … [but] an overcooked steak, on the other hand, is a criminal act, like putting ketchup on foie gras.”

How to order steak properly

Getting steak cooked exactly as you want it isn’t foolproof. Few eaters are willing to go as far as filmmaker Barry Sonnenfeld, who once brought a catalog photo of a steak to Bowery Meat’s chef Josh Capon when he was at Lure Fishbar to show him how he wanted it done.

But it’s not difficult to try. Although it’s theoretically a cinch to ask for more fire on an undercooked steak, a customer should nudge the house to get it properly medium-rare the first time. Even a few minutes’ lag for one person at a table to “send it back” can be awkward for others who don’t. It’s also bad for the kitchen — and for the steak.

“Our goal isn’t to reheat or refire it,” said Porter House’s Michael Lomonaco, who turns out many cuts at around 120 degrees before resting. “The result isn’t the same when it goes back for further cooking.”

So what should you tell the waiter? Once again, experts disagree.

“Tell them you want it hot in the center, the color pink, and red with some brown toward the edges, and with a crust outside,” chef Laurent Tourondel recommends.

But Capon laughs off the idea of telling a server, for instance, “I’d like it red-pink in the center, fading slightly toward brown closer to the edges,” he says. “If anything, I’d ask if they cook true to temperature.”

I find nothing works better than to say “medium-rare-plus,” and reinforce it with, “That’s more than medium-rare but not medium.”

But at this rate, we soon might have to ask for it medium-well to guarantee it won’t be raw.