Finely shred the white and red cabbage and place them in a large mixing bowl.
Slice the cucumber into thin rounds or matchsticks and add it to the bowl.
Chop the green onions and mix them with the cabbage and cucumber.
In a small bowl, whisk together sunflower oil, vinegar, and salt.
Pour the dressing over the salad and toss everything together until well coated.
Let the salad sit for 5-10 minutes to allow the flavors to blend.
Taste and adjust seasoning if needed before serving.
Serve immediately or refrigerate for later—this salad gets better with time!