Press the tofu. Wrap the tofu block in a clean kitchen towel and press under a pan or heavy book for 15–20 minutes.
This removes excess water and helps the tofu crisp.
Preheat and prep. Heat the oven to 425°F (220°C). Line a baking sheet with parchment for easy cleanup.
Season and coat. Cut the tofu into 3/4-inch cubes. Toss with soy sauce, oil, a pinch of salt and pepper, then sprinkle on the cornstarch.
Gently toss until evenly coated.
Bake until crisp. Spread the tofu in a single layer on the sheet. Bake 25–30 minutes, flipping halfway, until golden and crisp at the edges.
Make the sauce. In a small bowl, whisk soy sauce, rice vinegar, sesame oil, maple syrup, sriracha (if using), broth, and cornstarch. Set aside.
Cook the veggies. Heat oil in a large skillet or wok over medium-high.
Add broccoli and carrots; cook 3–4 minutes. Add bell pepper and red onion; cook 2–3 minutes more. Stir in garlic and ginger for 30 seconds until fragrant.
Add the tofu. Transfer the baked tofu to the pan with the vegetables.
Sauce and thicken. Whisk the sauce again, then pour it in.
Stir gently. It will thicken and coat the tofu and vegetables in 1–2 minutes. If it gets too thick, add a splash of water.
Finish and serve. Turn off the heat.
Stir in green onions. Taste and adjust with more soy for salt, vinegar for tang, or chili for heat. Serve over rice or noodles.
Top with sesame seeds, herbs, and a squeeze of lime.