First, preheat your oven to 425°F and line a baking tray with parchment paper. Using the largest holes of a box grater, grate the super firm tofu straight onto the tray — this gives you long, ribbon‑like shreds that crisp beautifully.
Next, drizzle the tofu with tamari, rice vinegar, cornstarch, sesame seeds, and avocado oil. Toss it to coat well, then spread it into a single layer. Bake for 15 minutes, then toss and bake for another 5–8 minutes until golden and crispy.
In a large pot over medium‑low heat, warm the avocado oil and add the sliced onion with a pinch of salt. Cook until the onions soften and turn slightly golden, about 5 minutes. Add garlic, ginger, Fresno pepper, and scallion whites, cooking another 2 minutes until fragrant.
Add dried shiitake mushrooms and 3 ½ cups hot water, then bring the mixture to a boil. Reduce the heat and simmer for 15 minutes to deepen the flavor.
While the broth simmers, dissolve the miso and sesame oil in the remaining cup of water in a large measuring cup. Once the mushrooms are removed from the soup, stir in the miso mixture, lemon zest, and juice. Use an immersion blender to make the broth silky.
Place a scoop of warm cooked rice in a bowl and ladle the hot broth around it. Top with the crispy shredded sesame tofu and finish with a drizzle of sesame oil or extra scallion greens.