Cut the tofu crosswise into 12 slices. Place the tofu slices in a large nonstick frying pan over medium heat and cook for 5 minutes on each side. The tofu will brown slightly and lose some of its liquid. Transfer to a plate and let cool.
In a bowl, whisk together the milk, egg whites, 1/4 teaspoon of the salt and the pepper until well blended. On a large plate, combine the bread crumbs, white and black sesame seeds, and remaining 1/4 teaspoon salt. Mix until well blended. Dip a tofu slice into the milk mixture, and then dredge in the sesame seed mixture. Repeat dipping and dredging with the remaining tofu slices.
In a large nonstick frying pan, heat the oil over medium heat. Arrange the tofu slices in the pan and cook, turning once, until lightly browned, about 3 minutes on each side. Transfer to a plate and keep warm. Add the green onions to the pan and saute until they begin to brown, about 3 to 4 minutes.
Divide the green onions among individual plates. Top each serving with 3 tofu steaks and serve immediately.