Sauté the onion and garlic in avocado oil until fragrant.
Add the butternut squash, soy milk, and water. Stir until smooth and warmed through.
Mix in the miso, soy sauce, and sesame oil.
Add the mushrooms and bok choy and let simmer for a few minutes.
Cook the udon separately, then add to a bowl.
Pour the butternut squash miso broth over the udon.
Top with mushrooms, bok choy, green onion, and chili oil.