1 pound skinless, boneless chicken breast, preferably from a small producer of free-range chickens, cut into pieces 1/4 inch thick by 1 inch long
2 tablespoons finely shredded or minced ginger
2 tablespoons Shao Hsing rice wine or dry sherry
2 teaspoons soy sauce (low-sodium if desired)
2 teaspoons cornstarch
3/4 teaspoon sugar
1/4 teaspoon roasted and ground Sichuan peppercorns
1/4 cup chicken broth or water
2 teaspoons rice vinegar
2 tablespoons peanut or canola oil
1 tablespoon minced garlic
Zest of 1 orange
2 medium-size ripe tomatoes, cut into thin wedges, or 1 heaped cup cherry tomatoes, halved
3 cups baby spinach or chopped chard leaves, washed and dried
1/4 cup thinly sliced scallions
Salt to taste