Melt <quantity>1<unit>cup</unit></quantity> of unsalted butter over medium heat in a saucepan. Cook 20m stirring occasionally. Butter will take on the color of hazelnuts when ready

Transfer the butter to a bowl to cool down

The brown butter is ready

Rinse and remove beards from <quantity>1<unit>kg</unit></quantity> of black mussels

Bring <quantity>1<unit>cup</unit></quantity> of vegetable stock to boil

Add mussels. Cover with lid

Simmer the mussels until they open. Strain and reserve stock

Melt <quantity>1<unit>tbsp</unit></quantity> of butter on low heat. Add <quantity>5</quantity> chopped garlic cloves and <quantity>2<unit>tbsp</unit></quantity> of diced onion

Add <quantity>1<unit>tbsp</unit></quantity> of yellow mustard seeds

Add the reserved stock and <quantity>1⅓<unit>tbsp</unit></quantity> of apple cider vinegar

Reduce by ⅔

Add <quantity>¼<unit>cup</unit></quantity> of brown butter and stir to combine. Remove from the heat

Pick <quantity>¼<unit>bunch</unit></quantity> of parsley. Chop

Slice stalks from <quantity>¼<unit>bunch</unit></quantity> of flat leaf parsley

Pick mussel meat and transfer to bowl. Add the brown butter mixture

Add the sliced parsley, <quantity>1<unit>tbsp</unit></quantity> of capers and mix to combine. The Mussel Salsa Verde is ready

Enjoy with a mega tasty Pork Chop Schnitzel!