Place tofu between two plates, and weigh down with a heavy book. Allow tofu to drain for 1 hour, pouring out the expelled liquid every 20 minutes.
Whisk together the soy sauce, mirin, sesame oil, and rice vinegar in a small bowl. Heat the oil in a small pan over medium heat, stir in the garlic and ginger, and gently cook until lightly golden; stir into the soy sauce mixture.
Cut tofu into bite-sized pieces, and toss together with the tomato, onion, and cilantro. Pour in the dressing and toss to coat. Garnish with a sprinkle of sesame seeds.
