In a large bowl mix first 3 ingredients. Peel and slice cucumbers and onion and add to vinegar/water/sugar mix. Cover and refrigerate for 1 hour before serving. If all the cucumbers and onions are eaten reserve the vinegar/water/sugar mix and add fresh cucumbers and onion. My servings are an estimate, as I can eat the whole bowl myself :) The cooking time is actually the refrigeration time.