Cut both the tofu and cod into pieces about 1.5 inches long and .5 inch thick. Place tofu in one bowl and cod in another.
Divide next seven ingredients between the two bowls and toss gently. Take care not to break the tofu.
Heat half of oil in a wide, ninstick skillet. When hot, add tofu and fry over medium-high heat until golden and crispy, 8-10 mninutes. Turn so that all surfaces have a chance to color. When done, sprinkle with salt, remove to a plate, and cover to keep warm. Return pan to the heat.
Add remaining oil, add the peanuts and cod, and cook over high heat until cod is barely cooked, about 3 minutes. Return the tofu to the pan, add the scallions, and cook 1 minute more. Season with salt, then slide the tofu and fish onto a platter and garnish with lemon wedges if desired.