In a medium pot, cover tofu with water and bring to a gentle simmer. Remove from heat and set aside.
Heat oil in a medium skillet over medium heat. Add peas and scallion whites and saute, stirring, until peas are crisp-tender, about 2 minutes. Transfer to a medium bowl.
Mix in scallion greens, red pepper flakes, sesame seeds, garlic, sesame oil, soy sauce, sugar, and 1 tablespoon water. Season with salt.
Drain tofu and divide among plates. Top with pea mixture.