Bring vegetable broth to a simmer in a small pot over medium heat. Once simmering, reduce the heat to low to keep warm.
Prepare mushrooms, by breaking up any large bunches and tearing larger mushrooms into bite sized pieces.
Heat 1 tablespoon of olive oil in a large pan over medium heat. Cook mushrooms until golden brown (about 5-7 minutes), stirring minimally to get some good browning.
Set mushrooms in a bowl, drizzle 1 teaspoon of soy sauce over the mushrooms, toss to coat, and set aside.
In the same pan that you cooked the mushrooms, heat 2 more tablespoons of olive oil. Add diced onion and minced garlic and 1 teaspoon of salt. Cook for 3-5 minutes until onions are translucent and soft, stirring occasionally, scraping up any burnt mushroom bits from the bottom of the pan.
Add rice and stir to coat in oil. Add 1 tablespoon of mirin plus 1 teaspoon of soy sauce. Cook until reduced, about 1 minute.
Add ½ cup of warm broth to your rice, stirring frequently, until the liquid is nearly absorbed into the rice, about 2-3 minutes.
Continue to add broth to the pan, 1/2 cup at a time and stir until absorbed. Repeat this process until rice is creamy and tender, about 20 minutes.
Stir in miso paste, Forager Project Half & Half, and remaining 1 tablespoon of soy sauce. Add mushrooms to risotto, toss to combine. Ladle risotto into bowls and garnish with sliced green onions and sesame seeds.