Brown hamburger, drain and add taco mix according to directions. Cook until only small amount of liquid is left. Cool and refrigerate meat. In medium bowl mix dressing mix, milk and mayonnaise. Mix well and refrigerate.
When ready, in a large bowl mix lettuce, peppers, onion and tomato. Mix in taco meat, 1-1/2 cups cheese. Add ranch dressing.
Crush 2/3 of bag of Doritos and add. Mix everything well.
Top with remaining cheese and Doritos.
Cajun Country -- New Iberia, Louisiana