Squeeze the water out of the rehydrated shiitake and save the liquid in a separate bowl. Chop the shiitake and set aside with the other mushrooms.
Add the rest of the seasoning ingredients to the bowl with the leftover shiitake liquid. Mix well and set aside.
Heat oil in a deep pan or wok over medium heat. Add garlic, ginger, and the white parts of the green onions. Once fragrant (about 30-60 seconds), add eggplant and mushrooms. Cook until the mushrooms have released their liquid and the eggplant is tender.
Add tofu and seasonings and stir thoroughly. It's OK if some of the tofu breaks apart.
Mix together cornstarch and 2 tbsp water to make a slurry. Once the sauce in the pan is boiling, add the cornstarch slurry and stir to incorporate. As soon as the sauce thickens, turn off the heat. Top with the green parts of the green onions. Serve immediately.
Notes
MUSHROOMS: You can use any variety of mushroom you like. I usually use white button mushrooms or crimini mushrooms since they are readily available and affordable where I live.TOFU: Some mapo tofu recipes use soft/silken tofu. I prefer medium firm tofu since it has more of a bite to it but is still soft and bouncy. You can use silken tofu if you prefer, or a mix of both! VEGETARIAN OYSTER SAUCE: You can omit and add another 1-2 tsp of soy sauce.