Shred the cabbage finely and place it in a large bowl. Add carrots, onion if using, and chopped cilantro. Toss lightly to distribute evenly.

In a small bowl or jar, whisk together lime juice, oil, sweetener, salt, and pepper until smooth. Taste and adjust acidity or sweetness as needed.

Pour the dressing over the cabbage mixture. Toss gently until everything is lightly coated. The slaw should look glossy, not wet.

Let the coleslaw rest for 10–15 minutes. This softens the cabbage slightly while keeping its crunch.

Taste again and adjust seasoning. Add more lime or salt if needed, then serve chilled or at room temperature.