All across the country, restaurants are struggling to fill their kitchens. It's happening on the East Coast, in New York City, and in the Midwest, in Chicago; it's happening out West, too, in Los Angeles, San Francisco and Seattle. Good cooks, who were once in excess supply, are suddenly a lot tougher to find.

The truth is that despite what you might see on the Food Network or other cooking shows, being a cook is grueling work that's not for the faint of heart. The slowdown in immigration over the past five years has also made it harder for kitchens to find staff since the industry is deeply reliant on immigrant labor.

But there's another problem that's been bubbling up for decades: Many of the people who work the kitchen have been getting short-changed -- especially when compared to the wait staff serving customers.

"The back-of-house staff are typically underpaid compared to the front of the house," said Darren Tristano, executive vice president of Technomic, a restaurant industry research firm. "It's a really big issue."

Tipping the scale

On paper at least, cooks in this country are paid more than waiters. The median pay for cooks is about $10 an hour, according to the Bureau of Labor Statistics. For waiters, it's roughly $9 an hour. But those numbers don't tell the whole story -- because waiters are paid tips, and kitchen workers are not. And tips completely skew the comparison.

The government's estimate for how much waiters make includes a bit of guesswork about how much they earn from tips, since tips are often paid in cash, and things paid in cash tend to slip through the cracks. The Atlantic wrote about the issue earlier this year:

...the IRS estimates that as much as 40 percent of tips go unreported. It's hard to track for an obvious reason: Everyone likes giving and getting tips in cash. Nationally this adds up to as much as $11 billion in unreported (and untaxed) income.

Waiters, in other words, are probably making a lot more money than BLS data makes it seem. Pay Scale, which tracks salaries through crowdsourcing, estimates that in cities like Miami, Boston and San Francisco, waiters can expect to make $13 an hour in tips alone, on average. Elsewhere, tips can add well over $10 an hour to servers' salaries.

Waiters working in big cities understand this. But so do cooks, and they aren't happy about it.

"The fact that servers are making so much money in tips is certainly a reference point that causes cooks to be dissatisfied with their pay," said Michael Lynn, a Cornell University professor and one of the country's foremost experts on tipping. "That is absolutely true. It's the way it is."

The waiting game

Waiters aren't paid like everyone else. Unlike cooks, who are subject to the federal minimum wage, servers are instead compensated based on the assumption that they are going to earn some extra money on the side. Restaurants are required to pay their wait staff what is known as the tipped-minimum wage, which is $2.13 per hour.

The understanding is that tips will make up for the difference between the tipped and regular pay floor. But even when the tips don't make up that difference, waiters still make no less than the federal minimum wage because restaurants are legally required to pay the rest.

The truth, however, is that that rarely happens. The average base pay for waiters is $4.90, according to Pay Scale. What they make in tips is earned on top of that, and tips alone more often than not amount to a good deal more than the $7.25 federal minimum wage.

"It can be a very high-paying job," said Tristano. "Especially considering that many entry-level cooks earn at or near the minimum wage."

Kitchen workers aren't allowed to share tips. Early on, it was common practice for restaurateurs to pool together tips and then split them among their entire staff. It was also common for tips to disappear en route to the employees, likely into the pockets of management.

Realizing the need for regulation, the government intervened, creating a set of rules known as the Fair Labor Standards Act, which stipulates, among other things, that if tips are pooled, they can only be distributed among workers who "customarily and regularly receive tips." Cooks do not qualify. Neither do dishwashers or janitors.

"You can force a waiter to share a tip with a bus boy or bartender but not with someone in the kitchen staff," said Lynn. "It's illegal to split tips with the cooks."

Part of the reason for the measure was to ensure that there was no room for defrauding the public. If people think they're tipping the waiter but aren't, there's a lack of transparency. But mostly, Lynn said, it was a hasty response to the outgrowth of firms plucking tips away from servers.

"It was a less than optimal solution," he said. "It was patchwork. The problem is that it doesn't really benefit the people working the back of house."

Tristano agrees. "It's not working for cooks," he said. "It's not working for them at all, and that's never really been addressed."

Bridging the gap, even as it grows

The ark of tipping etiquette varies, depending on where you live, but it tends to bend upward. In many cities, the tip norm has crept up from 15 percent of the bill to 18 percent. Where 20 percent was considered generous, 25 percent is becoming the new standard. And that's only widening the gap between what waiters and cooks are paid.

"The more money servers earn from tips, the more customers are ultimately paying to eat out," said Lynn. "That pressures restaurants to charge lower prices, which, in turn, makes it even harder to pay cooks."

The number of chefs and restaurateurs who are concerned about the current system is growing. Last year, a panel that included celebrity chef Michael Chiarello and Shake Shack founder Danny Meyer discussed how the tipping system is creating pay inequality within restaurants. In 2013, New York Times restaurant critic Pete Wells wrote a passionate takedown of tipping.

"The restaurant business can be seen as a class struggle between the groomed, pressed, articulate charmers working in the dining room and the blistered, stained and profane grunts in the kitchen," Wells wrote.

Many restaurants have responded by breaking from the traditional tipping system. Some have gotten rid of tips altogether. For instance, Sushi Yasuda in New York City added this note to its credit card slip a couple years ago: "Sushi Yasuda’s service staff are fully compensated by their salary. Therefore gratuities are not accepted." Many others have simply added a flat service charge.

But there are other, more unique adaptations, too. One restaurant in Los Angeles, Alimento, added a kitchen service line to its bills, so that customers could leave a tip for both the servers and the cooks. Chef and owner Zach Pollack shared a picture of the new receipts on Instagram earlier this year.

Another restaurant, Magpie Cafe in Sacramento, did the same.

Still, this particular practice has its flaws. It can be confusing for customers who are not used to the extra ask. Without a social norm, or clear-cut obligation in place, it's unclear if they will leave anything at all for the kitchen staff, especially since it's not the cook who will be coming to collect the check.

"That's tough," Lynn said. "I think it really comes down to the question of why consumers tip. Do they do it to help someone out? Or do they do it to help someone out that they can see? I don't know."

The best way to resolve the conflict, Lynn said, is probably to just pay cooks more and raise menu prices accordingly. There's no formula, and the practice can be hit or miss, but now that cooks are in short supply, better pay might be the only way to entice them.

"You need to pay more if you want to attract people. That's why you have a competitive system," he said. "The restaurants that get it right — that pay cooks well, raise prices and still manage to make a profit — will succeed, and the ones that don't will fail."

That may be the case, but finding the sweet spot won't be easy. Restaurant prices are fairly elastic, according to Tristano. Raising prices by three percent over the course of a year (a $15 dish by 45 cents) is something consumers don't tend to notice. Even a five percent increase is okay, he said. But anything more than that, and restaurants risk losing customers.

"If you're talking about a 10 percent hike, some people are just going to go elsewhere," Tristano said. "It can be a losing game."

"Cooking jobs are kind of like teachings jobs," he added. "They've been low-paying and underappreciated for a long time. I'm not sure that's going to change."