In a bowl, mix together the cabbage, carrots, pepper, and scallions.
In a small bowl, mix together sugar, rice vinegar, red pepper flakes, salt, and pepper. Heat just until the sugar dissolves (1 minute in the microwave). Pour the dressing over the cabbage.
Drizzle the sesame oil over the top of salad. Toss the coleslaw until well mixed. Taste for seasoning and add more salt and black pepper if you like.
Cover the bowl and refrigerate.
Recipe Notes
To pack for a picnic: use a slotted spoon to transfer the slaw to a plastic container, leaving behind the excess liquid.