Toss the pears with the orange juice in a large nonreactive bowl and set aside. Heat the oil and saute the shallots over medium-low heat for 20 to 30 minutes, until softened and slightly carmelized. Drain the pear slices and gently toss with the Grand Marnier, chives, ginger, and salt and pepper to taste. Fan out attractively on a serving platter, and top with the shallots.
Preheat the oven to 400°F.
Combine the panko with the curry powder. Dip the arctic char into the flour, shake to remove any excess, and place the fillets into a baking dish. Pat the panko onto their surfaces, and drizzle with the melted butter. Pour 2 Tablespoons of water around the fillets. Bake for about 12 minutes, or until the char is cooked through and the bread crumbs are browned.
Arrange the char over the pears, so that the pear design is visible. Sprinkle with the walnuts, if desired.