When done, the stock should be nice and cloudy. You can actually just stop here and eat the soup and meat like it is. See my post for Hearty Beef Soup (Gogiguk) on how to make the most delicious plain beef soup. Take out the brisket and let it cool.
Serve with some rice, kimchi and something not spicy like this tofu side dish.
My Yukgaejang(육개장) is on the less spicy side. Add more chili powder and also more sesame oil to make the chili oil layer on top that you will probably see in many restaurants. I personally don’t care much for that much oil layer on top but it's totally up to you. Korean spicy beef soup tastes better the next day. Store leftovers in fridge for few days or freeze for later.