Start by soaking the dried shiitake mushrooms in boiling water for at least 15 minutes until softened. Press the extra firm tofu between paper towels to remove excess moisture for about 10 minutes, then slice and carve out the center of each block.

In a large skillet, heat 2 tablespoons of toasted sesame oil over medium heat. Sauté minced garlic and diced onion for 2–3 minutes until fragrant and golden. Add soaked and diced mushrooms with carrots, cooking for another 4–5 minutes until tender. Stir in mashed tofu and season with soy sauce, vegetarian oyster sauce, ground pepper, and cornstarch slurry. Cook until thickened, about 2 minutes.

Take each hollowed tofu block and fill it tightly with the flavorful filling. Ensure filling reaches the edges for even cooking. Set stuffed tofu blocks aside.

Heat about 1/3 cup of oil in a large frying pan over medium heat. Once hot, place stuffed tofu blocks in the pan, frying each side for about 3–4 minutes until golden brown and crispy. Transfer to a paper towel-lined plate to drain excess oil.

In the same skillet, reduce excess oil, retaining just a tablespoon. Pour in 1.75 cups of water along with soy sauce and sugar, bringing to a gentle simmer. Mix remaining cornstarch with 2 tablespoons of room temperature water to create a slurry and stir into the simmering sauce, thickening for about 2–3 minutes.

To serve, place the stuffed tofu on a plate and drizzle generously with the sauce. Add chili garlic sauce if desired, garnish with chopped scallions, and serve hot over rice or noodles.