From My Bowl

 Prep: Preheat the oven to 425F and line a baking sheet with a silicone mat or parchment paper. Tear the tofu into bite-sized chunks for a more chicken-like texture, or cut into small cubes. 
Tofu: Add the tofu to a medium bowl and add in the oil and tamari. Toss with a spatula until evenly coated, then sprinkle the cornstarch on top and toss again. Transfer to a baking sheet and spread out the tofu pieces so they aren’t touching. Bake on the top rack of the oven for 30 minutes, flipping the tofu halfway through. 
Sauce: Once the tofu has gone into the oven, begin prepping the sauce. Warm the sesame oil in a medium pan over medium heat. Once warm, add the garlic, ginger, and optional red chili flakes. Sauté for 60 seconds, then add in the orange juice, brown sugar, tamari, vinegar, and orange zest. Bring to a simmer over medium heat and cook for 3 to 5 minutes. Mix the cornstarch with the water until dissolved, then add the slurry to the sauce and simmer for another 3 to 5 minutes, or until the sauce has thickened and can coat the back of a spoon.
Serve: remove the tofu from the oven and add it to the pan, coating all sides of the tofu in the glossy orange sauce. Serve warm, over rice or as desired. Leftovers will keep in the fridge for up to 5 days.