Naruto and his son, Boruto, could be main characters. Boruto might not understand his father's love for the ramen shop at first, but as the story progresses, he comes to appreciate it. Another character could be Shikamaru. He might be there to relax and have some ramen while also using his intelligence to solve any problems that arise in the shop, like a sudden shortage of ingredients.
One possible plot could be that a new and mysterious ingredient is discovered in the Naruto world. This ingredient is added to the ramen in the shop, and it gives those who eat it special powers. Naruto and his friends then have to protect the ingredient from villains who want to use it for evil.
One possible reason could be that he's had a bad experience with the taste. Maybe the ramen was made wrong one day and it left a really bad impression on him.
It could be a fanfiction that focuses on a character in Naruto experiencing withdrawal symptoms related to ramen. Maybe Naruto himself is deprived of his beloved ramen for some reason and the story explores how he copes.
Naruto could use his shadow clone jutsu to multitask in the kitchen. One clone could be chopping vegetables, another boiling the broth, and he himself could be preparing the noodles. His speed and agility from being a ninja would also help him serve customers quickly.
Yes, there are some out there. You can start by looking on fanfiction websites like FanFiction.net or Archive of Our Own. Just search for 'naruto ramen ban' in their search bars and you'll likely find a variety of stories. Some might be about Naruto being banned from his favorite ramen place for some wacky reason, like he accidentally caused a food fight or couldn't pay his bill.
One reason could be that it's overused. If there were too many fanfictions focusing on Naruto and ramen, the community might want to encourage different storylines.
In the Hidden Leaf Village, a ramen eating contest was announced. Naruto was the first to sign up. As the contest began, Naruto grabbed a huge bowl of his favorite miso ramen. He slurped it down with great gusto, his cheeks puffed out like a chipmunk. His friends cheered him on. Sasuke watched with a smirk, secretly impressed by Naruto's appetite. In the end, Naruto won by a landslide, his stomach full but his spirit even fuller.
One interesting Naruto ramen fanfiction could be about Naruto opening a ramen chain across the ninja world. He uses his popularity and his love for ramen to bring people together over bowls of delicious ramen.