Fire up enough charcoal to form a single layer beneath the fish. Combine all the marinade ingredients in a lidded jar, and shake the jar well.
Lay fillets in a single layer in a nonreactive pan. Pour marinade over the fish, and let the fish sit at room temperature for 30 minutes.
Drain fillets, reserving marinade. Bring the marinade to a boil, and then simmer it for several minutes.
When the charcoal is covered with gray ash, place the fillets on the grill. Cook the fish until it is opaque and flaky, about 4 to 5 minutes per half-inch of thickness. Turn the fish over halfway through the cooking time, basting with the marinade then and shortly before the fish is done.
Serve fish garnished with orange wedges and a sprinkling of orange zest.