Briefly rinse dried wood ear mushrooms to remove any dirt or grit that might be hiding in them. Place them in a small bowl of warm water and let them soak until fully rehydrated (about 20 mins). Drain, shake off any excess water, then slice them into thin strips. Set aside.
In a large pot (at least 4 quarts), heat chicken broth over medium heat until it reaches a boil.
While broth is heating, place black garlic in a small bowl and mash it with a fork. You are aiming to turn it into a paste, but it does not need to be perfectly smooth.
Once broth has reached a boil, ladle 1 cup of it into the bowl with the black garlic. Add coconut aminos and cornstarch, then whisk until fully blended. Pour back into the pot.
Reduce heat to a simmer. Add asparagus and cook until it just starts to turn tender, about 6 minutes. Add wood ear and cooked crawfish meat, and simmer for another minute or until crawfish is heated through (do not boil). Take care not to overcook, or the the crawfish will turn rubbery. Season with Cajun seasoning, salt and black pepper. Remove from heat.
Serve garnished with sliced green onion and torn fresh cilantro leaves.