1. Prepare the potatoes: place quartered potatoes in a pot and cover with 1 in of water. Do NOT add salt. Bring to a simmer, then cover and cook for 30-45 mins or until you can easily pierce with a fork.
2. Prepare the dressing: meanwhile, add all dressing ingredients to a blender or food processor, and blend until relatively smooth. Cilantro leaves should be in small pieces. Taste and adjust as needed. Need thicker dressing? Add a couple more Tbsp of mayo. Thinner? Maybe a tsp of apple cider vinegar or another squeeze of lime or orange.
3. Cool potatoes: once potatoes are ready, remove from water with a slotted spoon, and let cool for 10-15 minutes. If you prefer peeled potatoes, peel after they've cooled. The skin should come right off. With your unpeeled (or peeled) potatoes, chop into ½ in cubes and add to a large mixing bowl.
4. Add dressing & chill: add half of your dressing dressing and scallions to your bowl of potatoes, and gently mix. Taste and decide if it needs more dressing. Then, cover and refrigerate for at least one hour (preferably overnight).
5. Enjoy!