2 pounds sweet potatoes, peeled and cubed
4 tablespoons lemon juice, divided
2 celery ribs, thinly sliced
1 (11 ounce) can mandarin oranges, drained
1 cup fat-free mayonnaise
2 tablespoons orange juice
1 tablespoon honey
1/2 teaspoon salt
1/4 teaspoon ground ginger
1/8 teaspoon ground nutmeg
1/4 cup chopped pecans