Sauté the garlic, pepper and onion in the olive oil until soft (5 minutes).
Blend or process the stock, yogurt, lime juice, avocado, salt and pepper
together with the sautéed stuff above. (You may need to do this in two batches).
Add the tomatoes, cuke and cilantro to the puree, and store in an air-tight
container overnight or until quite chilled.