Pat haddock fillets dry with paper towels.
Mix salt and flour together then place haddock fillets in flour mixture and pat all sides so that the haddock fillets are coated.
Heat pan on high heat until hot then add oil.
Carefully place fillets in pan and brown on all sides.
Once haddock fillets are golden set aside on a paper towel lined plate.
Add butter to pan and return to high heat.
When butter is almost completely melted add diced mushrooms, and saute picking up any residue from the sauteed haddock.
Cook mushrooms until they are almost cooked through.
Add garlic and toss. Lower heat a little if needed to avoid burning the garlic.
Saute mushrooms and garlic until the flavors meld together.
Add vegetable broth and miso and mix together to create a sauce.
Carefully place haddock fillets into the sauce and allow everything to heat through.
Taste sauce to make sure you are happy with the flavors, and adjust if necessary.
Spoon sauce over the haddock fillets and serve immediately.