Preheat the oven to 400 degrees F and line a baking sheet with parchment paper.
Then add the cubed tofu to a bowl with soy sauce, sesame oil, and cornstarch. Toss well until each piece of tofu is coated.
Bake the tofu in the preheated oven for 20 minutes.
While the tofu bakes, make the sauce. Combine all sauce ingredients except for the roasted peanuts in a small bowl or jar until it becomes smooth. The thickness may vary depending on the brand of peanut butter you use. Add small amounts of water little by little if it's too thick, and mix again.
Remove the tofu from the oven and transfer to a large bowl. Drizzle the sauce over the tofu and mix well until all pieces are nicely coated. I like to use a lid and shake until everything is evenly distributed.
Finally, sprinkle the roasted chopped peanuts over the tofu. Serve on its own or with rice and veggies!