In 2022, the chef Jean-Georges Vongerichten was working in the kitchen of Happy Monkey, his restaurant in Greenwich, Conn., when an employee pulled him aside. A critic was coming in.
“I’m always nervous when someone tries my food,” Mr. Vongerichten said. But this time was different. The critic was 8 years old, and he planned to order an item that wasn’t on the menu: a Shirley Temple.
After perfecting arroz con pollo and sour cherry mole, Mr. Vongerichten admitted that America’s favorite mocktail had slipped through the cracks. “The Shirley Temple is not something I grew up with in France,” he said. “We were not prepared.”
Mr. Vongerichten and his team invented a Shirley Temple recipe at the eleventh hour using small-batch grenadine, homemade ginger syrup and Tajín seasoning. The critic awarded it a 9.3 rating.
This is the effect of Leo Kelly, now 11, who has been reviewing the drink for roughly half of his life as the “Shirley Temple King.” In short videos on Instagram, and occasionally on TV, he ranks Shirley Temples on a 10-point scale, considering factors like color, carbonation and the quality of the grenadine.
The internet is awash with food reviewers who opine from dining booths and drivers seats. But perhaps few of them have studied a single item the way Leo has.
“I think that if restaurants see this, they can improve them,” he said in a recent interview over Shirley Temples at the Smith in Midtown Manhattan. “Not just for when I come in, but for everybody.”
Most restaurants and bars do not list a Shirley Temple on the menu, although almost any bartender can easily cobble one together.
When Leo started his account in 2019, the drink was in a bad place. “I was served lukewarm Shirley Temples,” he said. “It hurts me to say that.” Even with renewed interest in alcoholic Shirley Temples, progress has been slower than he hoped.
He filmed his first review when he was 6 years old and came up with the name for his account on the fly. He was sipping a Shirley Temple by the pool at Gurney’s, a luxury resort in Newport, R.I., when he asked his father to record a video.
“I thought it would be a hit,” said his father, Tom Kelly, a vice president at a sports and entertainment agency. “He has a personality that people love. That’s been since he was born.”
His parents manage his Instagram profile — with 240,000 followers and counting — and approach the account like an extracurricular activity. “This is not his job,” said Lisa Kelly, his mother. “This is his hobby.”
The reviews are only one part of his life, they said. He is also a son, an older brother and a student — and an actor who has leveraged his online fame to land auditions for “Law & Order S.V.U.” and the Bobby Farrelly film “Dear Santa.”
When middle schools were closed on Martin Luther King’s Birthday, Leo traveled from his home in Fairfield, Conn., to the Smith for a review. He looked a little like Iain Armitage in “Young Sheldon,” wearing skinny jeans and a gray cardigan that his mother had picked out.
The Shirley Temple on the table was about to be torn limb from limb. “It’s got a pretty good color,” he said as his mother filmed. “Maybe a little too red. Unfortunately, it is lemon-lime soda, and it does have a little more grenadine than I want it to.” He rated it a 6.1.
While he accounts for ambience and service, he said, the bulk of a rating is based on the taste and appearance of the drink. He favors ginger ale over lemon-lime soda and deducts points for various missteps, such as serving a drink in a plastic cup, using store-bought grenadine or garnishing with fewer than three cherries.
“This is just my opinion,” Leo said. “I’m not going to come for anybody who likes lemon-lime soda.”
To keep his ratings honest, he typically visits restaurants without notice, and his parents pay for all of the meals that appear in his reviews. Occasionally, he dines out wearing a low-brim cap or a fake mustache (which seems unlikely to help a child maintain anonymity).
“It’s a simple drink, but there are a million ways to get it wrong,” he said. Only one Shirley Temple has ever received a perfect score: at the Lotte New York Palace hotel in Midtown. Santa Claus made it.
His ratings can have surprising consequences for restaurants. In 2019, Leo gave the Shirley Temple served at a LongHorn Steakhouse a 5.0 for having zero cherries. When the review went viral four months later, executives took note, updating the recipe at more than 500 locations. They are now made with five cherries.
Tyler Hall, a marketing manager in Boston, learned about Leo the hard way earlier this year, when one of his company’s restaurants, Sonsie, was featured in a review. At first, he thought the video was sweet. As he watched, he realized it was a takedown.
Leo critiqued the color and complained about carbonation. He thought the grenadine tasted off and counted one and a half cherries — a first in his career. “3.1.”
The review rippled through the Lyons Group, which operates Sonsie and 15 other restaurants in the area. Shirley Temples at Sonsie are now made with canned ginger ale or Sprite instead of fountain soda to ensure proper carbonation. Its bartenders are working on a homemade grenadine.
“We want that feedback, and we want to respond to it,” Mr. Hall said. “It doesn’t matter if it’s a kid or an adult.”
To Leo, that’s the fundamental purpose of the critical enterprise. “The reason for being a critic is to better whatever you are reviewing,” he said. “To better cinema, to better Shirley Temples, to better anything.”