Using a tofu press or a tea towel and some heavy books, press the tofu for about 15 minutes to remove excess water. While your tofu is pressing, preheat your oven to 400 °F and line a baking sheet with a silicone baking mat or parchment paper. Set it aside.
After your tofu has pressed, cut it into cubes, place it in a mixing bowl with the cornstarch and toss everything to coat.
Dump the cornstarch-coated tofu onto your lined baking sheet and spread each cube out so they aren't touching each other. Spray the tofu with cooking spray and bake for cubes for 30-40 minutes, flipping halfway through until browned on the outside.
While the tofu it baking, prepare the sweet and sour sauce by whisking together all of the sauce ingredients in a bowl.
Pour the sauce into a skillet and heat over medium heat. Once the tofu has finished baking, add the cubes to the sauce and stir everything to coat. Stir the tofu over the heat until the sauce has thickened and everything is warmed through, about 2-3 minutes.
Serve immediately with coconut rice and roasted broccoli...or however you desire!
Notes
If you have any leftover tofu, you can store it in an airtight container in the fridge for 2-3 days. To reheat it, simply microwave it for about 1 minute.