The culinary arts are analogous to the old saying, "One man's trash is another man's treasure," in that the subjectivity of what tastes good lies in the mouth of the person tasting it. Making a Korean marinade holds true to this principle as the best Korean marinade is dependent upon whom you are cooking for. Recipes found online and in print can be good starting points.
Regardless of which personal twists you prefer to customize your marinade with, there is a general recipe that you can follow for Korean marinades. This recipe encompasses herbs and spices common to Korean cuisine, composed of salt, garlic, and ginger. Additionally, you can add sesame oil and soy sauce along with gochujang and doenjang. Gochujang and doenjang are traditional Korean foods, referring to red chili paste and bean paste, respectively.
You should also consider the type of dish when choosing a Korean marinade. Questions such as "Do I want this dish to be sweet" or "Do I want to make this dish spicy" may give clues toward the ratio of ingredients to use. Trial and error is likely the best way to ultimately perfect a Korean marinade; however, following traditional guidelines of Korean cuisine will make for a less bumpy road to culinary success.
Korean cuisine originated from the prehistoric culinary practices native to the region where North and South Korea now exist. Most international cuisines draw from a number of social, political, and geographical influences, which may cause similarities but also some significant disparities. For example, many Asian food practices overlap in the use of rice and small-grained pasta, whereas traditional American food may differ more significantly from Korean than perhaps Taiwanese food.
There is also significant culinary variation among the different provinces of Korea, just as California cuisine may differ from that of New Jersey in the United States. The type of province or style of Korean food you wish to make should contribute to the recipe you select to make a Korean marinade. Once you identify the goals of the marinade, it will be easier to decide on a specific recipe or improvisation.
The Internet and cookbooks are probably the two best resources for finding a Korean marinade recipe. Authenticity issues with the Internet can become an obstruction, but if you can successfully find a legitimate source, you'll find a plethora of helpful tips and information at your disposal regarding a Korean marinade. Cookbooks found online or in bookstores will also highlight the best advice for perfecting artful combinations of simple ingredients in preparing the best Korean marinade possible.