This is a sauce my mom made one night that we demand every time she makes asparagus. I love it on ANYTHING, and as long as you have the ingredients on hand, it's SO simple to make!
(good on other veggies, too)
Start with light or FF sour cream (I've used plain yogurt, too) in a small bowl.
Add dijon mustard to taste (you're looking for a little "bite" but not something really spicy). Then add shredded parmesan cheese to the mixture until it's firm like dip, but will still fall off a spoon.
Sorry I don't have measurements for this--it's a very flexible recipe. I've made a tiny amount for two small servings of asparagus or a huge bowl for a group. It's just delicious!