Melanie's Golden Gazpacho

Peel the tomatoes and gently remove their seeds. Chop the tomato flesh very finely or pass it through a food mill (do not puree in a blender or processor) and place it in a large bowl. Stir in the stock, onion, garlic, and lime juice. Taste the soup and season with salt and pepper. Fold in the avocado and chill the soup for at least one hour. Remove the soup from the refrigerator, ladle into soup bowls, and top each serving with a generous tablespoon of olive oil and a sprinkling of chives.