Melt butter in large, heavy pot or Dutch oven over medium-high heat.
Add mirepoix, mushrooms, and barley and saute until until they begin to brown (approx. 20 minutes).
Add flour to pot and stir for five minutes.
Gradually mix in broth and bring to a boil, stirring frequently.
Reduce heat to medium and simmer until barley is tender and soup is beginning to thicken (approx. 40 minutes)
Mix in parsley, dill, and whiskey and season to taste with salt and pepper.