Heat oven to 425°F. Position two racks in the middle of your oven.
FOR THE CRISPY SHROOMS: Line two sheet pans with parchment paper and scatter with mushrooms and drizzle about 2 tablespoons of olive oil on each sheet pan, toss, and salt your shrooms. Roast in the oven for 35 minutes (rotating halfway through), until the mushrooms are brown and crispy. Remove from the oven and set aside.
SHROOM DRESSING: Meanwhile, whisk together 1 tablespoon of olive oil, 2 tablespoons of white miso, 1 tablespoon of rice vinegar, 2 teaspoons of white sugar, and 1 teaspoon of soy sauce. Set aside for later.
As the mushrooms crisp in the oven, heat 3 tablespoons of olive oil in a large skillet or braiser over medium-high heat. Add the Chinese sausage and cook until it is partially done and the fat has rendered. Stir in the onions and let them cook undisturbed for 2 minutes. Reduce the heat to medium-low and continue cooking the onions for an additional 8 minutes, stirring occasionally, until they are softened and beginning to brown. Add the garlic and red pepper and cook for 5 more minutes, then increase the heat to medium-high.
Stir in rice and cook for 1 minutes, letting the rice soak and toast in the Chinese sausage renderings. Add white wine and cook for about 1-3 minutes, scraping up browned bits, until the liquid has reduced by about half. Add 3½ cups of broth, ¼ cup of white miso, and 3 tablespoons of Soy Sauce. Bring to a boil, then cover and reduce heat to low. Simmer for 10 minutes.
After 10 minutes, uncover the rice, stir gently to re-distribute the liquids, then place in the oven and bake on the middle rack for 15 minutes.
Quickly remove the pan from the oven and turn the broiler on high. Place the skillet back in the oven and broil for 4–6 minutes, watching VERY carefully, until rice is crisped and deeply browned but not burned.
Just before serving, stir the roasted mushrooms, sliced scallions, and the miso dressing together and spoon over the crispy rice.
