Drain the extra-firm tofu and press it between paper towels for 15 minutes to remove excess moisture.
Cut the tofu into 1-inch cubes and toss them in a bowl with the cornstarch until lightly coated.
Heat half of the sesame oil in a large non-stick skillet or wok over medium-high heat.
Add the tofu cubes to the skillet and sear for 3-4 minutes per side until they are golden brown and crispy.
Remove the tofu from the pan and set it aside.
Add the remaining sesame oil to the same pan, then add the broccoli florets, sliced bell peppers, and edamame.
Stir-fry the vegetables for 5 minutes until they are tender-crisp.
Add the minced garlic and grated ginger to the pan and cook for 1 minute until fragrant.
Return the crispy tofu to the pan and pour the tamari soy sauce over the mixture.
Toss everything together for another minute to allow the sauce to thicken slightly and coat the ingredients.
Serve immediately while hot and crispy.