I guess this is a copy cat recipe from Cafe Rio.
1 package of Buttermilk Ranch dressing prepared according to directions
1/2 bunch of cilantro
juice from one lime
1 clove garlic
Add all ingredients into a blender until smooth.
I actually used buttermilk and mayonnaise for the ranch dressing. It says you can substitute milk for the buttermilk but I like the tanginess that buttermilk adds to the dressing.