Bring a pot of water to a boil and cook the noodles according to the package instructions until chewy and al dente. Reserve about ½ cup of the starchy noodle water, then drain and rinse the noodles under cold water for 10-15 seconds to remove excess starch.
While the noodles cook, add the grated garlic, chopped green onion, sesame seeds, sugar, peanut butter, chili crisp, Japanese mayo, and soy sauce to a large bowl. Mix until combined.
Add 3-4 Tbsp of the reserved noodle water and stir until the sauce loosens into a creamy consistency. Add a little more noodle water as needed, then season with a pinch of salt to taste.
Add the cooked noodles to the bowl and toss until evenly coated in the sauce.
Top with chopped green onions, a soft-boiled egg, and any other toppings you like.
