Tofu Stir-Fry

In a medium pot of salted boiling water, simmer tofu for 2 minutes. If using frozen tofu, simmer until completely defrosted. Remove from heat and let drain in a colander lined with paper towels. When cool enough to handle, gently squeeze and pat dry. If using frozen tofu, use firmer pressure to squeeze out water. Cut tofu into bite-sized pieces, then toss together with soy sauce, sesame oil, and black pepper in a medium bowl. Once liquids are absorbed, toss tofu with cornstarch.  In a large skillet over medium-high heat, heat 2 tablespoons oil. Add tofu and let cook until golden on all sides, turning occasionally, 7 to 8 minutes. Season with salt and pepper, and remove from skillet and set aside.  Heat remaining 1 tablespoon oil and add in garlic and ginger and cook until fragrant, 1 minute. Stir in string beans, carrots, broccoli, red pepper, and green onions. Cook until tender, about 8 to 10 minutes. Season with salt and pepper. In a small bowl, stir together soy sauce, sesame oil, water, brown sugar, and cornstarch. Return tofu to skillet and add sauce mixture to pan. Stir and cook until slightly thickened, 2 minutes.