Press and drain the tofu. Then break it into small pieces and allow it to drain further. Then combine the tofu pieces in a covered container with the corn starch and toss to coat.
Saute the coated tofu on medium heat in a few tablespoons of oil until golden brown. Then remove from the pan and place on a plate with a paper towel to degrease a little.
To make the sauce, combine all the sauce ingredients except for the cornstarch slurry, in a wok or pan. Bring to a gentle boil and then add the cornstarch slurry. Mix until the sauce thickens. Then, add the tofu and toss to coat.
Serve over white rice and garnish with sesame seeds and green onions.