Mix together the broth, soy sauce, sesame oil, honey, and sriracha in a small bowl. Mix 1 tablespoon of cornstarch with 1 tablespoon of water in another small bowl to form a paste, and then stir into the sauce. Cut tofu into small cubes.

Put a thin layer of cornstarch on a plate. Dip the tofu cubes into the cornstarch, coating the pieces lightly all over. Heat 2 tablespoons of the oil in a large skillet or frying pan over medium-high heat. Add the tofu cubes, and pan-fry for around 5-6 minutes on each side, or until crisp and golden.

Remove tofu to a plate. Put broccoli, onion and garlic into the hot pan and stir-fry for 4 minutes. Add the sauce and then the tofu and cook a few minutes, stirring until well coated and thickened.