Start by preparing all the vegetables. Thinly slice the cabbage, bell pepper, and carrot. Chop the green onions and mince the garlic and ginger.
Heat the vegetable oil in a large skillet or wok over medium-high heat.
Once the oil is hot, add the minced garlic and ginger. Sauté for about 30 seconds until fragrant.
Add the sliced cabbage, bell pepper, and carrot to the skillet. Stir-fry for about 5-6 minutes until the vegetables are tender but still crisp.
Pour in the soy sauce and sesame oil, and add the red pepper flakes if using. Stir well to combine all ingredients.
Cook for another 2-3 minutes, seasoning with salt and pepper to taste.
Remove from heat, and toss in the chopped green onions just before serving.
Transfer the stir-fried cabbage to a serving bowl and enjoy!