Trim the cabbage, then shred it. To shred, cut the cabbage in half, then slice each half into thin slices and separate the slices with your hands into strips.
Place the cabbage strips in a colander and rinse them.
Transfer the rinsed cabbage to a large, deep skillet without drying it off - the water adhering to the cabbage will allow it to steam. You can add a tablespoon of water to the bottom of the pan, but I usually don't find it necessary.
Turn the heat to medium-high and cover the skillet. When the cabbage starts to steam, which should take about a minute, lower the heat to medium.
Steam the cabbage, covered, for about 5 minutes. Uncover, stir, and cook it for 2 more minutes to allow any remaining water to evaporate. If there is still too much water in the pan, drain the cabbage into a colander and return it to the skillet.
Add the butter, garlic, salt, and black pepper, stirring to combine.
Cook for 2 more minutes, stirring, until the butter has melted.
Garnish, if desired, with dried parsley and red pepper flakes. Serve warm.
Video
Notes
You really do need to cook the cabbage gently over medium heat. If the heat is too high and the pan gets too hot, the cabbage might dry out, stick to the bottom of the pan, and even burn. So make sure you keep the heat to medium. If needed, add a bit of water (1-2 tablespoons) to the bottom of the pan.
You can keep the leftovers in the fridge, in an airtight container, for up to four days. Reheat them gently in the microwave at 50% power.