Remove the outer leaves of the cabbage and rinse it under cold water.
Cut the cabbage in half, then slice it into thin strips.
Heat olive oil or butter in a large skillet over medium heat.
Add sliced onions and sauté until translucent.
Stir in minced garlic and cook for an additional minute.
Add cabbage strips to the skillet, stirring well to combine.
Season with salt, pepper, and optional red pepper flakes.
Cook for about 10-15 minutes, stirring occasionally, until tender and slightly crispy.
Add soy sauce or vinegar during the last few minutes for extra flavor.
Remove from heat and serve warm.