Slice the mushrooms into 1/4-inch thick pieces. If you’re using extra large king oyster mushrooms you’ll need to slice these into half (horizontally) before slicing them into thin pieces.
Prepare Sauce/Marinade
Simply mix all the ingredients together in a bowl. Feel free to adjust the seasoning to your taste.
Add the sliced mushrooms to the marinade. Leave the mushrooms to marinate for at least 20 minutes. You can leave these to marinate overnight in the fridge but do note that the mushrooms will continue to release liquid.
Do not discard the excess sauce/marinade.
To Cook:
Heat a large cast iron pan or skillet over medium. Once hot, add some oil.
Place the pieces of marinated mushroom one-by-one and lay them flat on the pan. Leave the mushrooms untouched for 3-4 minutes or until lightly charred and then flip over to repeat on the other side. Once nice and lightly charred on both sides, remove the mushrooms from the pan.
Repeat this for the rest mushrooms, in batches, if they do not all fit in your pan.
Once all the mushrooms are lightly charred. Place them back into the pan and then pour in the remaining sauce/marinade. Leave the mushrooms to cook in the sauce until it starts to thicken and glazes the mushrooms.
Turn off the heat and serve the mushrooms with rice or other carbs and veggies of your choice. Best enjoyed while hot!