Toss the pork in a medium bowl with 2 Tbs. of the soy sauce, 2 Tbs. of the sherry, the ginger, the garlic, and the red chile flakes. Cover and set aside, tossing occasionally, while chopping the vegetables as directed above.
Heat a wok or a large skillet over medium-high heat. Add 2 Tbs. of the oil. When the oil is very hot but not smoking, toss in the vegetables. Cook, tossing constantly, until just tender, about 6 min.; scoop them out with a slotted spoon and pile onto a plate. Add the remaining 2 Tbs. oil to the wok and heat until very hot. Add the pork mixture and liquid and toss until the meat is lightly browned and just barely cooked through (it will cook more later), about 4 min.
Put the vegetables and any accumulated juices back into the wok and toss with the pork until hot, about 1-min. In a small bowl, whisk the broth, the remaining 1 Tbs. soy sauce and 2 Tbs. sherry, and the cornstarch until blended. Pour this into the pan and cook, stirring until the sauce is thickened and clear, about 2 min. Taste and adjust the seasonings. Garnish with the cilantro, if you like, and serve with hot rice.