Place the broth, hoisin sauce, vegan fish sauce, ginger and red chili flakes in a large bowl and whisk until combined. Add the sliced mushrooms and toss to coat. Set aside for 10 to 15 minutes to quickly marinate.
While the mushrooms are marinating, prepare the slaw. In a large bowl, whisk together the rice vinegar, soy sauce, sesame oil, ginger and agave until combined. Add the cabbage, cucumber, carrots, and pear, tossing to coat thoroughly in the dressing. Set aside.
Heat a large sauté pan over medium-high heat. Using a slotted spoon, transfer the marinated mushrooms to the hot pan, letting any excess marinade drip back into the bowl. Reserve the remaining marinade.
Cook the mushrooms, stirring occasionally, until tender and slightly caramelized, 5 to 6 minutes. Remove and set aside.
Heat the oil in the same pan over medium-high heat. Once the oil is hot, add the diced onion and cook until translucent, 2 to 3 minutes.
Next, add the shaved tofu and garlic and continue to cook, tossing occasionally, until the tofu is lightly brown and slightly crisp around the edges, 10 to 15 minutes.
Pour in the reserved mushrooms and marinade and bring to a gentle simmer.
Reduce the heat to medium-low and continue to simmer, stirring occasionally, until the sauce has reduced and thickened and coats the back of a spoon, 5 to 8 minutes. Remove from the heat and let cool at room temperature for 5 to 10 minutes before serving.
To build your tacos, place 2 to 3 spoonfuls of the mushroom and tofu mixture onto a warmed tortilla. Top each taco with slaw and fresh minced cilantro. Enjoy!