Place the tofu on a plate, cover it with some paper towels, top it with a cutting board and then place a weight on top of it. Let it sit for 15 minutes and then pat dry it before cooking.
Cut firm tofu into large cubes (about ½ inch). Pat dry with paper towels and set aside. Pour the marinade sauce over the tofu cubes and rest for 15 minutes. In a plastic bag, combine the tofu cubes with cornstarch and toss to coat
Meanwhile, cut broccoli into florets. Bring some water (about 5 quarts) to a rapid boil with a couple of teaspoons of salt. Cook the broccoli florets for two to three minutes in boiling water. By doing so, we can keep the broccoli bright green in color. Prepare a large bowl of cold water and ice, drain the broccoli florets, stir fry with minced garlic for two minutes, and then set the food aside.
Heat cooking oil in a large frying pan over medium-high heat until hot but not smoking. Add tofu pieces, working in batches if necessary, so as not to overcrowd the pan, and lower the heat if the oil begins to smoke. Cook until golden brown on all sides, about 5 minutes per batch. Transfer cooked tofu pieces to a plate lined with paper towels when they are brown. Repeat this process with the remaining tofu pieces until all of them have been fried.
Heat cooking oil in the wok and add in the minced garlic and dried red pepper until fragrant, pour in all the sauces, and let it simmer until thickened.
Add fried tofu cubes and toss the mixture until each tofu piece is coated in sauce.
Garnish with green onions and roasted sesame seeds.
Serve warm and enjoy!