In a small bowl, stir teriyaki with wasabi powder and rice vinegar.
Set teriyaki mixture aside for 10 minutes to allow flavors to blend.
In a medium bowl, stir 1 tablespoon of the teriyaki mixture with cucumbers.
Stir in sour cream. Set aside.
Brush both sides of the catfish with remaining teriyaki mixture.
Place on a lightly oiled baking pan.
Broil about 4 inches (10 cm) from heat for about 7 minutes.
Remove from oven.
Top with cucumber mixture.
Sprinkle generously with coriander.
Serve with steamed green beans.