Prepare the vegetables: Finely chop the Napa cabbage into small pieces or use the Thermomix chop bottom. Grate the carrots and dice the red bell pepper.
Combine all vegetables in a large mixing bowl.
Prepare the Dressing: In a small saucepan whisk together the oil, vinegar, sugar, salt and pepper until the sugar is dissolved.
Combine everything together: Pour the dressing over the vegetables and toss well until evenly coated.
Rest: Cover and refrigerate for at least 2-4 hours, or overnight for the best flavor.
Serve: Toss again before serving and enjoy chilled.