1 pound pork tenderloin, cut crosswise into 1/8-inch-thick strips
2 celery ribs diagonally cut into 1/4-inch-thick slices
6 oz snow peas diagonally cut into 1/4-inch-thick slices
1/2 lb bok choy, cut into 1/4-inch-thick slices (leaves and ribs separately)
1/4 lb mushrooms cut into 1/4-inch-thick slices
1 onion, halved lengthwise and into 1/4-inch-thick strips
1 green bell pepper cut into 1/4-inch-thick strips, then halved crosswise
1/4 lb mung bean sprouts, rinsed and drained
1 (5-oz) can sliced water chestnuts
1 (5-oz) can sliced bamboo shoots
1/4 cup chicken broth
Salt and pepper to taste
Stir together garlic cloves, 1 tablespoon oyster sauce, soy sauce, salt, and 1/2 teaspoon cornstarch in a bowl. Stir in pork and marinate 15 minutes.
Keep cut vegetables separate. Heat a wok over high heat until a bead of water dropped onto cooking surface evaporates immediately. Drizzle 1 teaspoon vegetable oil around side of wok, then stir-fry celery, seasoning with salt, until crisp-tender, about 2 minutes. Transfer celery to a large bowl. Reheat wok and stir-fry each remaining vegetable separately in same manner (but allow only 1 minute for bean sprouts), adding 1 teaspoon oil to wok before each batch and seasoning with salt. When stir-frying bok choy, begin with ribs, then add leaves and 1 tablespoon water after 1 minute. Transfer each vegetable as cooked to bowl with celery.
Stir together chicken broth, 1 teaspoon oyster sauce, and 1 teaspoon cornstarch.
Reheat wok over high heat until a bead of water evaporates immediately. Drizzle 1 tablespoon vegetable oil around side of wok, then stir-fry pork until just cooked through, about 2 minutes.
Return all vegetables to wok and toss. Make a well in center, then stir broth mixture and add to well. Bring sauce to a boil, undisturbed, then stir to combine with pork and vegetables. Serve immediately, with cooked rice.