Mash avocados and blend in lemon juice and salt, mixing well. Spread evenly in a bowl or on a serving plate to the edges.
Beat cream cheese with an electric mixer until smooth and creamy. Stir in sour cream and taco seasoning mix, blending well. Spread over the avocado layer. Sprinkle with cheddar cheese, tomatoes, green onions and black olives.
Keep refrigerated until serving time. Serve with tortilla chips.