Pat chicken breasts dry with paper towels and season with kosher salt.
Heat a pan to medium-high heat with some avocado oil.
Sear chicken on both sides until cooked through, then remove from the pan.
Turn down the heat to medium low and add in butter.
Add in miso paste, lemon, water, and dijon and whisk until smooth.
Add in half of the chives, and season with a pinch of salt if needed.
If the sauce gets too thick, add in a splash of water.
Slice chicken and pour sauce over and top with remaining chives.
Serve with an arugula parmesan salad.