plain yogurt, preferably made with whole milk, 3/4-1 c
mayonnaise, regular or light, 2-3 T
crumbled gorgonzola, stilton, or other blue cheese, 2 oz or to taste
fresh garlic, 1 clove
scallions, white and green parts of 2-3, roughly chopped
fresh ground black pepper to taste
combine all in food processer and whiz around til combined. if you do not use whole milk yogurt, this will be really runny (hey, whole milk yogurt is still better for you than sour cream). cottage cheese would also work for some of the dairy, and would probably result in a thicker dip. this has a very strong garlic/scallion bite to it, so you might not want to add all of them until you've mixed and tasted a couple times.
you could deliberately make this on the runny side and it would make fine salad dressing.
great with crudite, might be good with fries, but probably not so good with potato chips.