Heat the oven to 300ºF.

• Trim and discard the root from the leek. Cut the tough green tops into 1-inch-thick slices and rinse. Cut the white portion in half lengthwise, then into ¼-inch-thick half-moons, and rinse.
• Husk the corn. Cut the kernels from the cob and reserve; cut the cob in half.
• Separate the fresh shiitakes into stems and caps; reserve the stems and thinly slice the caps.

In a pot, combine the green leek tops, stripped corn cob, fresh shiitake stems, dried shiitakes, 3½ cups water, and 1 teaspoon salt. Bring to a boil, reduce to a simmer, and cook until flavorful, 14 to 16 minutes. While the vegetable stock cooks, toast the hazelnuts.

On a sheet pan, spread the hazelnuts in an even layer and toast in the oven until lightly browned and fragrant, 12 to 14 minutes. Remove from the heat and let cool. With the side of a knife, lightly crush them. While the nuts toast, make the risotto.

• Coarsely chop the garlic.
• Pick the basil leaves and cut into thin strips. Discard the stems.
• Zest and juice half the lemon; cut the other half into wedges.

In a pot over medium heat, warm 2 tablespoons oil until hot but not smoking. Add the white leek pieces, season with salt, and cook, stirring occasionally, until tender, 5 to 7 minutes. Add the garlic and cook until fragrant, about 30 seconds. Stir in the sliced fresh shiitake caps and the Arborio rice and cook until the rice is opaque, 2 to 3 minutes. Stir in ¼ cup wine or water, and cook until the liquid has been completely absorbed, about 1 minute.
Strain the warm vegetable stock directly into the pan, discarding the solids. Bring to a boil, reduce to a simmer, cover, and cook until most of the liquid has been absorbed and the rice is just tender, 13 to 15 minutes. Stir in the corn kernels, basil, lemon zest, 2 teaspoons lemon juice, and the pecorino. Season to taste with salt and pepper.

Transfer the risotto to individual bowls, top with the hazelnuts, and serve with the lemon wedges.