Lightly season chicken pieces with salt and place in vacuum seal bag, making sure pieces do not touch. Put some sliced onion, shredded scallion and a slice of ginger on top of each piece; seal bag.
Sous vide for 1 1/2 hours at 64 degrees celsius if using dark meat, or 61 degrees celsius if using white meat; remove and let cool; cut chicken into 1/2"-3/4" slices; put in a deep container.
Mix together chicken broth and rice wine and pour over chicken; sprinkle with 1/2 teaspoon salt. Cover and refrigerate overnight. Serve cold.
Garnish with fresh cilantro sprigs or thinly julienned scallions, shredded carrots and shredded daikon radish, if desired.