In a small mixing bowl, whisk together 2 tablespoons cornstarch (if using) with the powdered ginger, garlic powder, salt, and pepper. Sprinkle the mixture over all sides of the cubed tofu.
Heat a large skillet (I use cast iron) on medium heat. Drizzle with oil and once hot, add the tofu. Cook for tofu 2 - 4 minutes on each side, or until lightly browned. Once done, transfer tofu pieces to paper towels.
In a medium mixing bowl, whisk together the marmalade, tamari, and rice vinegar.
In a separate skillet (or you can use the same one if first wiped clean, but I don't normally use cast iron for this part), over medium heat, add the sesame oil. Once hot, turn the temperature to medium-low. Add the minced ginger and garlic. Sauté for 1 minute, careful not to let them burn.
Add the marmalade mixture to the skillet and turn the heat back to medium (unless the sauce starts to boil, then you'll want to keep the temperature down). Sift in cornstarch, whisking the entire time.
Turn heat to low until the sauce has thickened. Stir in the tofu and turn the heat back up to medium or medium-low. Heat tofu in sauce for 3 - 5 minutes or until thoroughly reheated. If desired, serve over or alongside rice (or cauliflower rice) and/or steamed broccoli. Top with toasted sesame seeds and/or chopped green onions.