Start by preheating your oven and shredding the super-firm tofu using a box grater. Toss the shredded tofu with tamari, rice vinegar, cornstarch, sesame seeds, and avocado oil. Make sure every piece is evenly coated for the best texture.
Spread the tofu evenly on a lined baking sheet. Roast until golden brown and crispy, flipping halfway through. This step creates the crunchy topping that contrasts beautifully with the broth.
Heat avocado oil in a large pot over medium heat. Add onion, ginger, garlic, Fresno pepper, and scallion whites. Cook until fragrant and softened to build a flavorful base.
Add dried shiitake mushrooms and hot water to the pot. Bring to a gentle boil, then reduce the heat and simmer. This allows the mushrooms to infuse deep umami flavor.
Whisk miso paste with a small amount of hot water until smooth. Stir it into the soup along with sesame oil, lemon zest, and lemon juice. Remove mushrooms before blending if desired.
Use an immersion blender to create a smooth, velvety broth. Adjust salt if needed. Serve over cooked rice and top with crispy sesame tofu.