In a medium bowl mash avacado with a fork. Stir in green chilies, 1/2 the garlic, lemon juice, sour cream and salt. Cover and refrigerate overnite.
To serve, 1 hour before, in a large bowl, tear lettuce into bite size peices. Add tomatoes, green onions, olives, other 1/s of garlic and cheese. Spoon avacado mixture over salad; toss lightly. Before serving Sprinkle corn chips over salad.