In a pot over medium-high heat, sauté garlic, ginger, and the white parts of the green onions (save the green parts for topping) in sesame oil until fragrant and tender, about 2-3 minutes.
Add in miso paste and chili paste and continue to cook, stirring often, for another minute.
Deglaze the pan with mirin, then pour in the konbu dashi and 1 tbsp soy sauce. Bring to a boil.
Reduce heat to low, cover and allow to simmer while you prepare your noodles and add-ins.
When you're ready to serve, add in soy milk and cook an additional 2-3 minutes, or until heated through. Taste and add additional soy sauce if you like it saltier.