This is called Ensalada de Noche Buena (Christmas Eve Salad).

2 cups jicama, peeled and cubed
4 oranges, peeled, sectioned, and cut into chunks
4 scallions, chopped
1/4 cup cilantro, chopped
Juice from the salad
1 tablespoon Mexican lime juice
1 tablespoon vegetable oil
2 tablespoons sour cream
Salt

Mix jicama, oranges, onions and cilantro and allow to chill for several hours.

Before serving, remove the salad from the refrigerator and bring it to cool room temperature. Pour off excess liquid into a small bowl. Add remaining ingredients. Stir to combine them well, then toss with the salad. Add only a small amount of salt to the dressing since the salad is primarily sweet. Combine the dressing with the salad at the last minute so that more juice does not drain.