Remove outer peel from onion. 

Cut onion in half, cutting through the stem.

Taking each half one at a time, lay on a cutting board, flat side down.  Cut from stem to stem into thin strips. Use your hands to break apart and set aside. 

Bring a large cast iron skillet to medium-high heat and add 1 tablespoon of ghee (or butter or olive oil).  Let melt and coat the pan.  

Once the pan is hot, add the onion.  Sprinkle with kosher salt and ground black pepper (approx. 1/4 teaspoon of each).  Move the onions around fairly constantly, allowing them to cook down about 3-4 minutes.  You can cook longer if you want the consistency of your onions to be softer. If you want the consistency of your onions to be more firm with almost a bit of crunch, then cook them less.

Add another tablespoon or two of ghee (or butter or olive oil) and the sliced mushrooms. Season again with kosher salt and ground black pepper. 

Stir fairly constantly, allowing the mushrooms to cook down, about 3-4 minutes. 

Taste and adjust seasoning as desired, add additional ghee or butter or cook a little longer if you have not reached your desired consistency. 

Serve immediately with steak, pork chops or chicken!