Slice ends off of your cucumber then thinly slice them into 2-3 mm disks.
Add the cucumbers to a bowl, then mix together with salt and let them rest for 10 minutes. Drain out the excess water and taste for seasoning. If too salty, rinse and pat them dry with a paper towel before continuing to step 3.
In the same bowl with the drained and dried cucumbers, combine with soy sauce, korean red pepper flakes, sugar, sesame seeds, onion, scallion, grated garlic, and sesame oil. Mix the cucumbers and seasonings until well combined and the cucumbers turn a deep red color.
Marinate the cucumbers for 10 minutes in the dressing before serving and enjoy!
Notes
KEY TIPS:Cucumber Shape/Size
I like to cut these into 1/8" thin discs (2-3mm) because they're thin enough to soak up the dressing, while being thick enough to stay crunchy. However, you can cut them to whatever thickness or even shape you prefer - there is no wrong way! Other popular shapes I've seen are:
half moons
thick round slices
2" thin diagonal slices
Salt Your Cucumbers and Drain the Excess Water
Salting the cucumbers will draw out excess moisture from the cucumbers, which helps keep them crisp in the final salad. Make sure to let the salted cucumbers rest for 10 minutes to really draw out the moisture.
PLEASE drain the excess water from the salted cucumbers - this will help the cucumber salad doesn’t become watery and soggy! The salt acts as an agent to draw out excess water from the cucumber as well as keep them crisp in the salad. Do not skip this step!
STORAGEStore your Korean Cucumber Salad (Oi Muchim) in an airtight container in the refrigerator for 2-3 days. Please note that as they continue to sit, the cucumbers will lose water. This can lead to excess liquid, sometimes dilution of the flavors, and the cucumbers become softer. I like to eat my Korean Cucumber Salad (Oi Muchim) within the first 1-2 days, as I prefer my cucumbers on the crunchier side. You may not mind this (my wife likes them softer, with the flavors more melded together.)