Remove as much moisture as possible from the tofu by wrapping it in a towel and pressing firmly. Slice tofu lengthwise to create three rectangular pieces. Lay each piece flat in the bottom of a baking dish.
Whisk tamari and spice mix together in a small bowl. Pour over tofu and marinate for at least an hour.
Preheat the oven to 450°F. Place the tofu in an oiled roasting pan. Roast on the top rack of the oven for 10 to 12 minutes. Transfer tofu to plates and garnish with sesame seeds and green onions. Serve immediately.
YIELD: 3 servings I PREP TIME: 5 min I COOK TIME: 12 min I TOTAL TIME: 20 min