Place the avocados, vegetable stock, lemon rind and juice into a food processor and blend to a thin purée. Pour into a large bowl and set aside.
Place the tomatoes, cucumber, peppers and garlic into a food processor then blend to purée, season to taste.
Add the tomato mixture to the avocado puree and mix thoroughly. Cover and chill for 1 hour, then serve garnished with chives.