Begin by draining and pressing your tofu. Wrap it in paper towels or a clean kitchen towel and place something heavy on top. Let it press for at least 15 minutes to remove excess moisture.
Meanwhile, rinse the rice thoroughly under cold water, swirling with your fingers until the water runs clear. This removes excess starch and prevents the rice from becoming gummy.
Cook the rinsed rice according to package directions, either in a rice cooker or on the stovetop. Once cooked, let it sit covered for 10 minutes before fluffing with a fork.
While the rice cooks, prepare the teriyaki sauce. In a small saucepan over medium heat, combine soy sauce, mirin, brown sugar, minced garlic, and grated ginger.
Bring the sauce to a gentle simmer, stirring until the sugar completely dissolves. In a small bowl, mix the cornstarch with cold water until no lumps remain, then slowly pour this slurry into your sauce.
Continue simmering the sauce for 3-5 minutes, stirring frequently, until it thickens enough to coat the back of a spoon. Remove from heat and set aside.
Cut the pressed tofu into 1-inch cubes. Heat the vegetable oil in a large non-stick skillet or wok over medium-high heat.
Add the tofu cubes to the hot pan and cook for 2-3 minutes on each side until golden brown and crispy on the outside.
Pour half of the teriyaki sauce over the tofu and simmer for 2 minutes, gently turning the tofu to coat all sides. Transfer the glazed tofu to a plate.
In the same pan, add the vegetables in order of cooking time: carrots first for 1 minute, then bell peppers for another minute, finally broccoli for 2-3 minutes, until all are crisp-tender.
To assemble the bowls, place a generous scoop of rice as the base, arrange the teriyaki tofu and vegetables in sections around the bowl, drizzle with the remaining sauce, and garnish with sliced green onions and toasted sesame seeds.
Let the assembled bowls rest for 3-5 minutes before serving to allow the flavors to meld and the sauce to slightly thicken.