Press the tofu for 15 minutes to remove excess moisture, then cut into 1-inch cubes.
Toss the tofu cubes with cornstarch in a medium bowl until each piece is evenly coated.
Heat the toasted sesame oil in a large non-stick skillet or wok over medium-high heat.
Add the tofu to the skillet and sear until golden and crispy on all sides, approximately 8 to 10 minutes.
Add the broccoli florets, sugar snap peas, and sliced red bell pepper to the skillet, sautéing for 4 to 5 minutes until tender-crisp.
In a small bowl, whisk together the tamari, minced ginger, minced garlic, red pepper flakes, and water.
Pour the sauce over the tofu and vegetables, tossing constantly for 1 to 2 minutes until the glaze thickens and coats everything.
Garnish the stir-fry with sesame seeds and serve immediately while hot.