Chances are, you still have at least one late-summer get-together left that calls for an easy appetizer. While opening a packet of just-add-sour-cream dehydrated soup may be tempting, we promise this dip is equally effortless--and much better for you. In it, a creamy, cool base of French feta, Greek yogurt and buttermilk is brought to life with tangy lemon and fresh chives. Served with crisp carrot and celery sticks, this dip just might bring that staid onion glop to tears.