Begin by pressing your block of extra-firm tofu. Place it between several layers of paper towels or a clean kitchen cloth and set a heavy flat object on top. Let it press for at least 30 minutes to release moisture.
While the tofu is pressing, ensure your rice is cold. If you're cooking rice fresh, spread it on a baking sheet after cooking and cooling, then refrigerate for at least 1 hour (though overnight is preferable).
Prepare all your vegetables: dice the carrots into small, uniform pieces about ¼-inch in size, chop the cabbage into thin strips, and slice the green onions diagonally, separating the white and green parts.
Mince the garlic and grate the ginger. Measure out your frozen peas and corn - no need to thaw them.
Once the tofu is pressed, cut it into 1-inch cubes.
Heat a large wok or skillet over high heat until it's very hot (smoking slightly). Add 1 tablespoon of sesame oil.
Add the tofu cubes to the hot wok, spreading them in a single layer. Let them cook undisturbed for 2-3 minutes until the bottom develops a golden crust.
Flip the tofu pieces and continue cooking until golden brown on all sides, about 8-10 minutes total. Remove from the wok and set aside.
Return the wok to high heat and add the remaining sesame oil, followed by the white parts of the green onions, minced garlic, and grated ginger. Stir-fry for 30 seconds until fragrant.
Add the diced carrots, cabbage, peas, and corn. Stir-fry constantly for 4-5 minutes until vegetables are tender-crisp and vibrant in color.
Break up the chilled rice with your hands to remove any clumps, then add it to the wok. Stir-fry with the vegetables for 2-3 minutes.
Pour in the tamari sauce and rice vinegar, then fold in the crispy tofu pieces. Continue stirring until everything is well combined and the rice starts to develop a slight crispiness around the edges.
Season with white pepper and give it a final toss. The rice should be heated through and have a golden color.
Garnish with the reserved green onion tops and serve hot.