The 3 red flags a sushi chef looks out for when he goes out for high-end sushi

• Chef Masaharu Morimoto shared red flags he looks out for when at a high-end sushi restaurant. 
• Rice should never be cold and the fish should never feel frozen or icy in sushi. 
• The wasabi should be freshly grated and "real," not the prepackaged stuff.

Chef Masaharu Morimoto told Business Insider there are specific details throughout a sushi-eating experience that show him whether he's actually at a high-quality establishment.

He opened up his first restaurant at 24 years old, and now, 44 years later, Morimoto owns multiple restaurants, has appeared on some of Food Network's most iconic shows including "Iron Chef," and has become synonymous with Japanese cuisine.

He told BI that the art of being a sushi chef "is a very important position in Japanese culture," and he takes traditional sushi seriously.

"In my experience, you don't even get to work with fish for many years," he said. "First, you have to learn how to prepare the rice perfectly, then you graduate to working with the fish."

So to help diners navigate the growing, multibillion-dollar sushi industry, Morimoto shared the top three red flags he looks out for when he's craving a high-end sushi experience — plus a few good signs you're at a spot with great food.

Cold rice is always a sign your sushi isn't going to be great

"Luxury and high-end restaurants will always make sushi rice throughout the evening so it's always the right temperature," Morimoto said.

For him, that means it's served anywhere from warm to room temperature as long as it's in compliance with the Department of Health.

"This temperature allows the rice to stick together when you shape and serve it," he added, "but the cool temperature of the fish and warm sushi rice achieves the umami experience."

As a chef, understanding that importance is paramount, Morimoto said. So if the rice is cold and hard, that could be a bad sign of everything else that's to come.

The fish shouldn't be even close to frozen when it's served

"For the art of serving exotic and/or seasonal higher-end sushi, the use of frozen fish is a must in so many ways nowadays," Morimoto said. "But the prep of service and proper thawing and shelf life management is more of the key."

He described the texture of frozen or near-frozen fish as trying to bite through a semi-frozen stick of butter.

Even when frozen ingredients are necessary, thawing them properly is crucial.

Wasabi should be freshly grated, not packaged

A high-end sushi restaurant also loses bonus points with Morimoto if it's not serving fresh wasabi.

"If you've tried fresh wasabi, you'll notice the difference," he said.

The chef said "real" wasabi has a fresh, slightly sweet flavor with a little bit of heat that adds a flavor-enhancing spiciness rather than flavor-masking when it comes to the fish it's applied to. Packaged wasabi, he added, tends to hold its heat longer and overpower the sushi or sashimi.

Texture-wise, Morimoto says the fresh stuff has a "very smooth, ground root consistency," whereas packaged "has more of a paste-like powdery texture."

"I would recommend always doing your best to use real wasabi for sushi," he told BI.

The marks of a quality, luxury sushi meal are easy to spot for Morimoto

When it comes to green flags, the chef says the best sushi restaurants tend to use seasonal ingredients, have simple menus, and feature a tranquil, minimalistic ambiance in line with the "common aesthetics of Japanese culture."

"Using ingredients that are in season allows for the sushi to be at its freshest and always filled with flavor," Morimoto told BI. "Luxury sushi should be the highest quality, made with fresh fish and other sea-based ingredients."

The chef said this also applies to the rice, "which should always be seasoned with a blend of vinegar, salt, and sugar."

Lastly, thoughtful presentation is almost as important as taste.

"To me, sushi is an art," he said. You can combine some of the best ingredients in a roll but ruin the dish by not plating it correctly.