In a large bowl, combine the shredded cabbage, oil, vinegar, salt, and pepper.
Using clean hands, massage and squeeze the cabbage for 1-2 minutes. This helps to break it down and tenderize it, allowing it to absorb the dressing.
Cover the bowl and refrigerate for at least 3 hours, or overnight for the best flavor. This allows the cabbage to marinate and soften.
Just before serving, stir in the chia seeds to ensure they remain crunchy.
Don't skip the massage! Squeezing the cabbage with your hands is a crucial step that tenderizes the leaves and helps them soak up all that tangy flavor.