Press the tofu: Wrap the block of tofu in paper towels. Place a plate or pan on top of the wrapped tofu, and put a couple of heavy books on top of that. Let the tofu press for 20-30 minutes. You can skip this step if you buy the high protein, super firm variety, which I recommend.
After pressing the tofu, chop it into 1/2 inch cubes. Slice/chop the garlic, ginger, onion, red bell pepper, carrot and broccoli florets. In a bowl, whisk together the sauce ingredients. Have everything close to the stove and ready to go.
In a large pan or wok, heat the sesame oil over medium-high heat. Add the tofu, and fry it for 5-10 minutes, until all sides are golden brown.
To the pan with the tofu, add the onion, garlic and ginger and stir for about 1 minute.
Add the red bell pepper, carrots and broccoli and cook for 3-4 minutes, stirring constantly.
Pour in the stir fry sauce, stir and cook for 1-2 minutes. Serve immediately with chopped green onions, sesame seeds, cashew pieces or peanuts, if desired.