Fill a rimmed plate or shallow plate with water and dip one spring roll wrapper at a time in the water until pliable but not floppy (about 20 seconds). Lay it on a lint-free towel or another plate.
Leaving about one inch along the edges, layer the crab or salmon (or half and half), cucumber, carrots, and avocado. Top with some Momofuku Chili Crunch sauce.
Roll the spring roll halfway, enclosing the fillings, and fold the sides in until fully wrapped.
Serve immediately with a sou sauce or store in the fridge for 1-3 days. Enjoy!