The original of this recipe was found in The Sweet Potato Lover's Cookbook, 1998. Preparation time does not include the time needed for the salad to chill.
Wash & peel the sweet potatoes, (Sometimes I peel 'em, sometimes I don't!) then cut them into 1-inch cubes & put them in a vegetable steamer.
Steam over boiling water 10 to 15 minutes or until tender but still firm. Set them aside to cool.
Scrub the apples, then core & cut them into 1-inch cubes. Put the cubed apples in a container with a lid, then add the lemon juice & sugar, tossing to coat the apples.
In a large bowl, combine the raisins, nuts, salt, sweet potatoes & apples.
In a small bowl, mix the yogurt & mayonnaise to make a dressing, then toss the dressing with the sweet potato-&-apple mixture before chilling & serving.