In a medium bowl, combine lobster, tomato, avocado and Caesar dressing. Mix together, adding salt, pepper, and lemon juice. Set aside. Blanch several whole chives by dropping in boiling water for 10 seconds. Slice tortillas into 1/4's with knife. Roll each tortilla quarter into a cone shape. Secure by tying blanched chive like a string around cone. Scoop lobster mixture generously into cone, filling up to top. Adorn opening of each cone with freshly chopped lettuce.