In a large bowl, mix the Teriyaki Sauce ingredients.
In a bowl large enough to hold the fish, add the fish, scallions, and half of the marinade and refrigerate for 30 minutes. Remove from the marinade and drain well.
Use the SAUTÉ function to sauté the scallions in 2 tablespoons of oil. Remove to a plate or bowl and keep warm.
Add the fish to the cooker and sear on all sides. Turn off the SAUTÉ setting.
Add the reserved scallions and marinade to the cooker. Close and lock the lid, turn the regulator knob to the PRESSURE position, and pressure cook on HIGH for 3 minutes.
When done, release the pressure and open the cooker. Serve immediately with scalions or seasame seeds as garnish if desired.