Trim plantain tips. Cut plantain into 2- to 3-inch lengths. Slit skin on each piece lengthwise, then remove, pulling slightly crosswise rather than down the length of the piece. Cut into 1/2-inch slices, then cut into 1/2-inch dice, more or less. Cut pork into pieces the same size. Halve onion through "poles," then cut lengthwise into slices. Mince garlic. Slice scallions thin.
Heat large nonstick skillet or wok over high flame. Add 1 tablespoon oil and pork; stir-fry until browned, about 2 minutes. Add plantain; brown on one side without stirring, about 1 minute. Then toss and cook until browned on all sides, another minute or two. Transfer to a platter; reserve.
Return pan to heat, add 1/2 tablespoon oil, the ginger, and garlic; stir-fry a few seconds. Add onion and cook a minute. Add remaining 1 tablespoon oil. Sprinkle in rice and toss 1 minute.
Add pork and plantain, tossing. Add scallions and 2 tablespoons cilantro. Sprinkle with 2 tablespoons soy sauce and sesame oil, tossing. Taste for seasoning, adding soy, cilantro, and sesame oil, as desired. Scoop onto a platter and serve hot.
Recipe courtesy of Elizabeth Schneider's VEGETABLES FROM AMARANTH TO ZUCCHINI (Morrow, 2001)