To make green tea, pour hot but not boiling water over tea bags and steep for five minutes. Use one tea bag for every 8 ounces (1 cup) hot water. In a deep skillet, simmer green tea, ginger, garlic and onion for 10 minutes. Salt and pepper the fish, and place the steaks gently into the poaching liquid. Adjust heat to a gentle simmer, and cook steaks 8-10 minutes until fish is slightly translucent. Remove fish. Serve with Green Tea Vinaigrette or with mayonnaise thinned with white wine vinegar and finely grated fresh ginger. Good accompaniments include hot brown rice and sauteed scallions.