1.Prep and Drain the Fruit :2 min.
Open the canned pineapple chunks, mandarin oranges, and maraschino cherries. Place them into fine-mesh strainers over the sink to drain completely. Extra juice will make the salad watery. Chop the pineapple into smaller bite-sized bits, and slice the stemmed cherries in half.
2.Smooth the Base :2 min.
Spoon 1 cup of sour cream into a medium-sized mixing bowl. Use a small whisk or spoon to vigorously beat it for a few seconds. This removes any initial lumps and makes it silky smooth so it coats the ingredients evenly.
3.Fold Ingredients Gently :3 min.
Dump the drained pineapple chunks, mandarin oranges, halved maraschino cherries, and miniature marshmallows into the bowl with the sour cream. Using a rubber spatula, gently fold the mixture from the bottom up. Be careful not to break apart the delicate mandarin orange segments.
4.Chill and Plump :2 hours.
Cover the mixing bowl tightly with plastic wrap or a fitted lid. Place it in the refrigerator to chill for at least 2 hours. During this resting time, the marshmallows will absorb moisture from the sour cream, plumping up and sweetening the dressing naturally.
5.Stir and Serve Cold :1 min.
Give the chilled salad one final, gentle stir right before serving to redistribute any settled juices. Portion it into dessert bowls and serve while perfectly cold.