Directions
Slice caps into ¼-inch wide strips.
Put broth, mushroom slices, carrots, ginger, celery and mirin into a medium saucepan.
Simmer over low heat, about 20 minutes. (Refrigerate covered up to several days.)
Melt butter in a separate medium saucepan over medium-low heat.
Stir in flour.
Stir in onion, apple, curry powder and cayenne.
Cook and stir over medium-low heat until onion softens, about 5 minutes.
Whisk the broth mixture (with vegetables) into the flour mixture.
Cook and whisk until the mixture comes to a boil.
Then reduce heat to very low; simmer, partly covered, about 15 minutes.
Season with soy to taste.