Unlike salads, we need to use starchy variety of potatoes for any soup recipes. For the reason, all the potato varieties do not have the same starch content. Potatoes with more starch does not hold the shape, disintegrates well while cooking further giving nice thick soups. So, Russet potatoes are of great choice, be it Mashed Potatoes or potato soups, Yukon gold or red potatoes also does the job well.