Maybe your steak was undercooked, or your soup came out ice cold. Regardless of the culinary faux pas, it can feel rude to send back food when you're at a restaurant. 

Shengxin Sun was a server and manager at restaurants for a decade in Columbia, Missouri, and has endured the full spectrum of reactions when it comes to customers who are dissatisfied with their food. 

"One time, a customer ate more than half of her food and said that she didn't like it and demanded that I have the kitchen staff make her something else," she says. "Her attitude was rude, and after explaining that she had ate most of the things on her plate, she said, 'well, I don't care, isn't the customer always right? I said I don't like it.'"

Sending back your food isn't an inherently hostile act, Sun says. You just have to do it in a respectful way.

Here is when she says it's OK, and not OK, to send back food, and how to do it politely. 

It's OK to send back food when…

If the food just doesn't "meet your expectations," it's understandable that you'd want to send it back. 

"When it does not taste good to you, or made not to your standard, like the meat is overcooked or the veggies are too raw, or if the food is contaminated in some way, then you should definitely send it back," she says. 

It's not OK to send back food when…

If you don't like your food, your plate should represent that sentiment. 

"Don't send food back when you've already eaten at least half the plate," Sun says. 

It also might not be appropriate to send back food if you're not the one paying for it, says Sara Jane Ho, a Harvard-trained etiquette expert and host of the Netflix show "Mind Your Manners." 

For example, if you're being treated to a prix fixe meal at a large dinner party, maybe don't send a dish back for not being exactly what you expected. 

"If you're invited to a nice dinner at a restaurant and someone else is footing the bill, then it's not your place," Ho says. Unless there is "something like a worm in it," you should just accept the free food. 

How to politely send your food back

The most important factor is tone, Sun says. Be calm and use words such as "please" and "thank you." 

"Start by saying nicely what your issue with the food is and ask politely if the server can send it back to either have the food remade or ask to have something else," she says.

You can also make a joke to ease the tension. 

"Sometimes I also think it helps to be funny if you feel awkward," Sun says. "I've started out with saying, 'I'm so not trying to be a Karen, but my food is (insert your issue here).' Then proceed to ask if they can fix it." 

Ho echoes that maintaining a respectful attitude is key. "Let them know you're not pleased but don't cause a scene," she says. "Keep a neutral tone." 

You also shouldn't ask for a refund, she says.

"I never say, 'oh, you should comp my meal,'' she says. "Leave the ball in the server's court and they should know what to do. And if they don't, it's not worth stressing over." 

You can simply not return to that restaurant in the future.

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