Preheat the oven to 425°F and line a baking tray with parchment paper. Grate the tofu over the largest holes to create shreds. Top the tofu with tamari, vinegar, cornstarch, and sesame seeds; drizzle with avocado oil. Toss to coat and spread the shreds in a single layer on the tray. Bake for 15 minutes, then toss and bake again for 5-8 minutes.

Heat oil in a large pot over medium-low heat. Add the onion with a pinch of salt and sauté for 5 minutes until softened and golden. Add ginger, garlic, pepper, and scallions; sauté until fragrant, about 2 minutes.

Add dried mushrooms and 3 1/2 cups water. Stir to combine, bring to a boil, then reduce to a simmer for 15 minutes.

In a large glass measuring cup, whisk together miso paste and remaining 1 cup of water with sesame oil until miso is fully dissolved.

Remove mushrooms from the soup pot, pour in the miso mixture, and add lemon zest and juice. Use an immersion blender to blend the broth smooth, then stir in remaining scallions.

To serve, add a scoop of rice to a serving bowl, ladle the broth around the rice, and top with crispy tofu. Garnish with extra sesame oil if desired.