Heat half the oil in a wide skillet over medium heat, and when hot, add the tofu. Sprinkle with salt. Brown the tofu on 2 or 3 sides—lots of recipes say to brown on all sides, but I rarely have the patience for that.
Transfer the tofu to a plate, and return the skillet to the heat. Add the remaining oil, followed by the garlic, ginger, and tomato paste. Cook for about 30 seconds, until fragrant, then stir in the tomatoes and soy sauce. Let simmer, bubbling away, until slightly reduced—about 10 minutes.
Stir in the tofu and taste for salt. Garnish with the scallion, then serve hot over rice.
