Drain pineapple, reserving juice; set pineapple aside. In a small saucepan, combine cornstarch and ginger; stir in pineapple juice until blended. Add honey and soy sauce. bring to a boil; cook and stir for 1-2 minutes or until thickened. Stir in lemon juice. Pour half into a small serving bowl.
Using long-handled tongs, moisten a paper towel with cooking oil and lightly coat the grill rack. Grill fillets, uncovered, over medium heat for 4-5 minutes on each side or until fish flakes easily with a fork, basting occasionally with glaze.
Meanwhile, grill pineapple slices for 2-3 minutes on each side or until heated through, basting frequently with glaze. Serve fish with pineapple and reserved glaze.