Heat the olive oil in a skillet over medium high heat on the stove.

Add the ground beef and taco seasoning to the skillet, and cook until completely browned. Drain and set the meat aside to cool.

Chop the iceberg lettuce, and place it into a large bowl.

Add the chopped tomatoes, cooked beef, Doritos and Catalina dressing to the bowl with the lettuce, and toss well to combine.

Serve topped with sour cream and guacamole if desired.