It's called oi muchim (오이무침), a hot cucumber salad. Cucumber is referred to as oi, and spiced mixture is called muchim.
You may make this easy side dish (banchan) with any type of crunchy cucumber, including Persian, English, Japanese, Korean, and pickled cucumbers (also known as Kirby).
It tastes great with any Korean dish and makes a quick replacement for kimchi.
Any crunchy cucumber would work well in this recipe, but my personal favorite is Korean cucumber.
In the summer, they are abundant in Korean markets nearby. They've been growing in my backyard as well.
Leo
Korean cucumbers have thin skin, a pale tint, and a slender, bumpy shape.
They're crispy, flavorful, and less seedy. They are my favorite kind of cucumbers, however I may be a little biased.