To make the crispy baked tofu, preheat the oven to 400° and line a baking sheet with parchment paper.
Place the tofu into a medium bowl and add the soy sauce, oil, cornstarch, and pepper. Toss to coat the tofu.
Arrange the tofu pieces in a single layer on the baking sheet.
Bake for about 30 minutes, turning halfway through, until browned and crispy.
While the tofu bakes, prepare the sauce. Stir 1/4 cup of water, brown sugar, soy sauce, rice vinegar, sherry, sesame oil, garlic, and ginger together in small saucepan.
Place the saucepan over medium heat and bring the sauce to a simmer.
Lower the heat and allow it to simmer for 10 minutes, until reduced by about 1/3.
Stir the chilled water and cornstarch together in a small bowl or cup. Stir the mixture into the sauce and allow it to simmer for about 1 minute more, until it thickens up a bit.
Remove the pot from the heat.
When the tofu is finished cooking, add it to the pot and stir to coat the tofu with sauce.
Divide onto plates with rice and steamed veggies. Top with sesame seeds and scallions. Serve.