Preheat the oven to 425F. Toss together the mushrooms with sesame seeds, garlic powder, onion powder, 1 tablespoon oil, and a generous pinch of salt. Spread the mixture out into a single layer. Bake for 15 mins, toss, and bake again for 5-10 mins, or until the mushrooms are slightly crispy around the edges. Squeeze the lemon juice on top and toss to coat.
Heat the remaining tablespoon of oil in a saucepan over medium low heat. Add the tomatoes along with a generous pinch of salt and sauté for about 5 mins or until the tomato halves start to breakdown and release their juices.
Add the scallions and corn then sauté along with the tomatoes for about 2-3 mins.
Pour in 3 ½ cups of water and add the dried mushrooms then stir to combine. Bring the broth to a boil, reduce back to a low simmer and cook for 10 mins. Carefully add the tofu to the broth and cook for 3-5 mins to warm through.
Stir in the miso paste: Add the remaining ½ cup water into a small bowl with miso paste and whisk together until no lumps remain. Remove the dried mushrooms then cut the heat. Pour the miso mixture into the soup and stir well to combine.
Drizzle a teaspoon of sesame oil overtop, then adjust the salt/miso to your taste. Ladle the miso soup between bowls top with the roasted mushrooms and a squeeze of lemon, then serve with rice and enjoy.
