Preheat the oven to 375˚F (190˚C).
First, prepare the puree. Cut the avocado in half, remove the pit and scoop out the flesh. Transfer to a medium bowl and toss with lime juice. Mash the avocado with a fork or a potato masher. Stir and mix with garlic, chiles, and sour cream until the spread is mostly smooth. Season with salt. Transfer to the fridge to cool.
Lightly grease a baking sheet with cooking spray. Place the wonton wrappers on the baking sheet in a single layer. Spray another thin layer of cooking spray over the wrappers. Bake in the oven for 6 – 8 minutes, or until crisp and dark brown. Remove from oven. Season with salt immediately. Set aside to cool briefly.
In a medium bowl, mix together shallot, ginger, ¼ teaspoon chiles, yuzu kosho, lime juice, olive oil & fish sauce. Taste and adjust with more chiles to your liking. Transfer to the fridge to cool.
Meanwhile, work on the yellowtail. Pat the fish gently with paper towel. With your sharp knife at a 45˚ angle, cut the fish with the grain into ½-inch slices. Try to cut each slice with one clean stroke. Then, cut the fish into ½-inch cubes. Add to the sauce. Season with salt. Toss gently to combine.
To assemble, spread the avocado on serving plates. Place crudo over. Top with radish slices and cilantro leaves. Serve immediately with wonton chips.