Season both sides of fish fillets with pepper and lemon juice (or salt).  Roll up fillets and place seam down on heatproof plate.  Sauté pistachios in oil in large skillet; remove from pan with slotted spoon, leaving oil.  Add celery, onion, garlic and ginger to skillet; sauté until nearly tender.  Add tomato and cook, stirring until hot.  Turn vegetables onto platter and keep warm.  Place plate of fish on rack over ½-inch boiling water in the skillet.  Cover and steam 7 to 9 minutes or until fish flakes with fork.  Transfer fish to the top of vegetables.  Sprinkle with roasted pistachios.  Serve with hot rice.