Press the tofu by wrapping in kitchen towels and placing something heavy on top for 15 minutes to remove excess moisture.
Crumble the pressed tofu into small bite-sized pieces with your hands, resembling ground meat texture.
Toss tofu crumbles with salt, pepper, and cornstarch until evenly coated.
Heat oil in a large wok or skillet over medium-high heat. Add coated tofu in a single layer.
Cook tofu undisturbed for 3-4 minutes until golden and crispy on the bottom, then stir and continue cooking until all sides are browned, about 8-10 minutes total. Remove and set aside.
Add more oil if needed to the same pan. Toss in garlic, Thai chilies, and red onion. Stir-fry for 1 minute until fragrant.
Return crispy tofu to the pan. Pour pre-mixed sauce (light soy sauce, dark soy sauce, vegetarian oyster sauce, and sugar) over everything.
Stir well to coat every piece. Cook for 2 minutes until sauce thickens slightly and clings to tofu.
Add fresh Thai basil at the very end. Stir just until wilted, about 30 seconds.
Serve immediately over steamed jasmine rice with optional fried egg on top.