4 Tbsp. Chilled butter, divided into four equal pieces
Chile oil or chile crunch (optional)
Prepare bean threads or rice vermicelli according to package instructions. Refresh with cold water and distribute the cooked noodles among four large soup bowls.
In a medium-size skillet heat the oil over medium-high heat and add the spinach. Cover and cook until wilted, about 2 minutes. Alternately, steam baby spinach in a microwave until wilted.
Season with salt, to taste, and stir in the chopped parsley.
Layer the cooked spinach over the distributed rice noodles.
Add the filets in one layer to the skillet, sprinkle with salt, and add the mushroom broth. Bring slowly to a boil, cover, and poach on a low simmer for about 1-3 minutes, until the fish is just cooked through (depending on the thickness of the fillet).
Layer one fillet over the spinach in each soup bowl. Cover and keep warm.
Add the cracked green cardamom seeds to the broth and reduce over high heat (uncovered) until the broth is reduced to about ¼ cup.
Whisk in the 4 Tablespoons of chilled butter, one Tablespoon at a time, until the butter is melted (do not allow the broth to come to a boil).
Correct for seasoning and pour over each portion of fish.