Blend mayo, yogurt, juice and cumin powder. If you are serving right away and don't plan to have leftovers, just mix in the rest of the ingredients. If you want a salad that will stand up, you should salt the carrots lightly and let them sit for at least a half-hour. Then come back, rinse off the salt and squeeze the carrots until they give up some of their excess juice. That way, they won't give off juice while sitting in the dressing, making it watery. Also, if you only have regular, thinner yogurt, you might cut back on the orange juice to just a 1/2 tablespoon.
The cumin gives a nice smoky edge to the simple carrot-orange sweetness, and of course there's the creamy-tangy aspect to the dressing. This is a very easy-going salad that would complement many other dishes. You could, of course, use segmented oranges instead of mandarin, but that's adding time and effort. And personally, canned mandarin oranges are a guilty pleasure, a weakness of mine. They're also good for the husband with Crohn's, since all the fibrous stuff is removed completely.