Preheat a grill or grill pan to medium. Season the fish cubes with the Old Bay seasoning and five-spice powder. Wrap the ham strips around the fish. Thread the fish alternately with the pineapple and onion onto metal skewers. Brush the skewers with oil, place on the grill, cover and cook, turning occasionally, until the fish is cooked through, about 10 minutes.
In a small saucepan, bring the tamari sauce, honey, lime peel, lime juice, ginger and sesame oil to a boil. Cook until thickened, about 5 minutes.
In a medium saucepan, bring the chicken broth and butter to a boil. Stir in the couscous, cover, remove from the heat and let stand for 5 minutes. Fluff with a fork and stir in the nuts and scallions.
Serve the skewers on the couscous and drizzle with the ginger-soy glaze.