Drain the tofu and place it on a plate lined with paper towels.
Cover with another paper towel and set something heavy on top to press the liquid out of the tofu
An iron skillet works well.
Let it rest there for 5-10 minutes.
Cube the tofu and place on a baking sheet with the vegetables.
Stir the tamari sauce together in a small bowl.
Drizzle 4 tsp. of the sauce over the tofu and vegetables.
Toss to coat.
Bake at 400° for 25-30 minutes.
Serve the tofu and vegetables over rice, drizzling the sauce over everything.
Pour the rest of the sauce into a saucepan and stir the cornstarch into the sauce.
The sauce will thicken more as it cools.