Put the rice and 2 1/4 cups water in a medium saucepan. Set the pan over high heat and bring the water to a boil.

Cover the saucepan, lower the heat to low, and cook the rice for 15 minutes. Take the pan off the heat and let it sit, covered, while you make the stir-fry.

Put the torn tofu in a medium bowl. Add 1 tablespoon of the soy sauce and 1 tablespoon of the cornstarch, then toss gently until the tofu is lightly coated.

Put the remaining 3 tablespoons soy sauce, the rice vinegar, the remaining 1 tablespoon cornstarch, the sugar, and 1/3 cup water in a small bowl. Stir until the cornstarch is fully mixed in and no dry bits remain.

Set a large skillet or wok over medium-high heat. Let the pan get hot for about 1 minute.

Add 1 tablespoon of the oil to the hot skillet. Swirl the oil around the bottom of the pan.

Put the tofu into the skillet in a single layer. Cook it without moving it for about 4 minutes, until the bottom is deep golden brown.

Turn the tofu pieces with tongs or a thin spatula. Cook for 3 to 4 minutes more, until the second side is browned and the edges look a little firm. Transfer the tofu to a plate.

Add the remaining 1 tablespoon oil to the skillet. Put the celery and red bell pepper into the skillet.

Cook the vegetables for 3 minutes, stirring often, until they are hot, bright, and lightly browned in spots but still a little crisp.

Add the scallion whites, ginger, and garlic to the skillet. Stir for 30 to 45 seconds, until they smell fragrant and the garlic no longer looks raw.

Stir the sauce in the small bowl again because the cornstarch settles on the bottom. Pour the sauce into the skillet.