Bring a large pot with water, about half way full, to boil and add some salt and a little bit of chipotle chili pepper powder (just a dash for flavor).
Cut potatoes into cubes that are about 1/2 inch in size or a little bigger. Add them to the pot. (If water does not cover all the potatoes, add a little more until potatoes are all covered.)
Cook over medium heat until potatoes are done but not over-done where they fall apart. (13-17 minutes. Check for doneness often. Easy way to check is to stick a fork or a butter knife in one of the potato pieces and if it goes through easy, it's done.)
Drain potatoes completely and add them to a large mixing bowl. Let them cool to room temperature.
Add corn, scallions, cilantro, some salt and black pepper. Mix carefully with a wooden spoon.
In a small bowl, whisk sour cream, mayo, buttermilk and pressed (or grated) garlic until smooth. Add chipotle chili powder, cumin, some salt and Worcestershire sauce. Mix well.
Fold sauce into potatoes until all evenly covered.
Taste to make sure you added enough salt and chipotle chili powder to your taste.
(If adding canned chipotle pepper, mince and mix it into the salad.)
Transfer into a large container with a lid and refrigerate until ready to serve. (At least 2 hours.)