Combine the water, vinegar, sugar and salt in a non-reactive saucepan over medium heat and bring to a boil. Combine the garlic, peppers, and celery heart in a food processor and puree for about 45 seconds. Add the hot liquid and puree again. Strain the mixture through a fine sieve and allow to cool to room temperature. Combine the cabbages and toss with the dressing.
Makes 4 servings.