Cook the potatoes in a pot of salted boiling water until done (~15 minutes)
Mix Greek yogurt, mayo, sambal oelek, jalapeno, vinegar, fish sauce, red pepper flakes, cilantro, and salt and pepper in a medium bowl until combined
Drain potatoes. As you transfer to the serving bowl, use your hand to smash the potato a bit in your palm (don't want to mash them, but breaking the skin allows the yummy sauce to soak into the starchiness of the potato)
Pour the sauce over the potatoes (I like serving right away so the potatoes are warm, but you can also chill the potatoes before putting on the sauce if you prefer it that way. This is a very flexible dish - you can do NO WRONG!)
Top with a little more cilantro and salt & pepper and serve