In a large mixing bowl, combine the finely chopped white cabbage, finely chopped red cabbage, grated carrots, sliced roasted red peppers, 2 chopped celery stalks, lemon juice, minced garlic, white vinegar, a splash of olive oil, salt, and pepper.
Using clean hands (or disposable gloves), toss the mixture thoroughly to coat all vegetables with the dressing.
Cover the bowl with plastic wrap and refrigerate for 1 hour to allow the vegetables to marinate and soften.
Remove the salad from the fridge and add the pine nuts, raisins, the additional 2 tablespoons chopped celery, chopped walnuts, and balsamic vinegar.
Toss everything together once more to combine, adjust seasoning with salt and pepper if needed, and serve.