Choris Dow asked me for a recipe to prepare Yakiniku/Korean BBQ Sauce and I’m glad to oblige.
There are many styles, and I hope you will be able to expand on the below suggestions:

RECIPE 1 (left of above pic) :

-Salt: 4 teaspoons
-Water: 2 tablespoons
-Finely chopped thin leeks: 8 tablespoons
-Sesame oil: 8 tablespoons

Mix well. Can be used at once

RECIPE 2 (Right of above pic):

-Red miso paste: 4 tablespoons
-Gochujang: 4 tablespoons
-Sugar: 2 teaspoons
Sesame oil: 5 tablespoons

Mix well. Can be used at once.

RECIPE 3:

-Soy sauce: 3 tablespoons
-Sugar: 1 tablespoon
-Japanese sake: 1.5 tablespoons
-Grated fresh garlic: 1 tablespoon
-Finely chopped thin leeks: 3 tablespoons
-Ground sesame seeds: 1 teaspoon
-Sesame oil: 1 tablespoon

Let marinate for 20 minutes.

RECIPE 4:

-Soy sauce: 50 ml
-Mirin/Sweet sake: 1 tablespoon
-Sugar: 1 pinch
-Seasme oil: 1 tablespoon
-Chili powder: 1 teaspoon
-Freshly grated ginger: 2 cloves.

Mix well and let marimate a little.

RECIPE 5:

– Soy sauce: 50 ml
-Sugar: half a tablespoon~1 tablespoon
-Japanese sake: 3 tablespoons
-Sesame oil: 3 tablespoons
-Mirin/sweet sake: 2 tablespoons
-Freshly grated garlice: 2~3 cloves
-Finely chopped onion: 1/4
-Black pepper: a pinch