Separate the Ramen Z tonkotsu broth and shirataki noodles from the packet.
In a small bowl, whisk the shio koji, shoyu, oat milk, and garlic powder together.
Mince the green onion white bases.
Add the neutral cooking oil to a small pot over medium heat. Once hot, add the minced green onion white bases and cook for 2 minutes. Make sure they do not brown.
Add the whisked tare ingredients to the pot with the minced green onion white bases and cook for another 2 minutes, bringing it to a simmer.
Add the tonkotsu flavor broth to another small pot over medium heat. Bring the broth to a boil.
In a ramen bowl, add the tare and then the tonkotsu flavor broth. Whisk the ingredients together.
Add the shirataki noodles to the bowl, followed by optional toppings and an aromatic oil.