Prepare the brown rice by combining the dry rice with 4.5 cups of the water in a large pot; bring to a boil, then simmer covered for 45 minutes until tender.
Press the firm tofu between paper towels for 15 minutes to remove excess moisture, then cut into 1-inch cubes.
Cut the chicken breasts into 1-inch pieces, ensuring they are uniform in size for even cooking.
In a medium bowl, whisk together the tamari, rice vinegar, maple syrup, arrowroot powder, the remaining 0.5 cup of water, minced ginger, minced garlic, and red pepper flakes to create the sauce.
Steam the broccoli florets in a steamer basket over boiling water for 5-7 minutes until they are bright green and fork-tender.
Heat the sesame oil in a large wok or skillet over medium-high heat.
Add the chicken and tofu cubes to the skillet in batches, searing until the chicken is cooked through and the tofu is golden and crispy on all sides.
Pour the prepared sauce over the chicken and tofu in the skillet, stirring constantly for 2-3 minutes until the glaze thickens and becomes glossy.
Serve the General Tso's mixture over the cooked brown rice with a side of steamed broccoli, garnishing with sliced green onions and sesame seeds.