Press the extra-firm tofu for 15 minutes to remove excess moisture, then cut into 2-centimeter cubes.
In a small bowl, whisk together the tamari, rice vinegar, pineapple juice, cornstarch, garlic powder, and ground ginger to create the sauce.
Heat 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 8 to 10 minutes, turning occasionally until the edges are golden and crispy.
Add the frozen broccoli florets directly to the pan with the tofu, sautéing for 5 to 6 minutes until the broccoli is tender-crisp and heated through.
Pour the prepared sauce over the tofu and broccoli, stirring constantly for 1 to 2 minutes until the glaze thickens and coats everything evenly.
Season the mixture with sea salt and black pepper.
Serve the sweet and sour stir-fry immediately over the warm cooked brown rice.