Bring 2 1/2 cups water to a boil in a saucepan or kettle. Place the dried mushrooms in a small bowl. Cover the dried mushrooms in the boiling water (you might not need all of the water), soaking until tender, approximately 20 minutes. Reserve 1 cup of the liquid.
In a medium-sized saucepan, heat up your stock to a boil, then turn down the heat until the liquid is simmering.
Heat a heavy-bottom saucepan or flat-sided skillet over medium-low. Layer with just enough olive oil to coat the bottom. Add the onions and sweat until translucent, 3-4 minutes, and then add the cremini mushrooms. Cook for an additional 3-5 minutes, until the mushrooms have softened and are starting to develop color.
Add the rice and turn up the heat to medium. Stir occasionally and let the rice toast for a few minutes with the other ingredients.
Add the wine, stirring briefly. Once the wine has mostly soaked into the rice, add the reserved mushroom liquid. Once that has absorbed, add a ladle of hot stock, along with the reconstituted mushrooms (reserve a few for garnish).
On medium-high heat, add one ladle of stock at a time. Stir periodically and swirl the pan, letting the liquid absorb almost completely before adding more. This process takes around 15 minutes.
Begin taste testing your rice for doneness when the stock starts getting low. You may not need all of it. When the rice is ready, add the Parmesan and truffle oil. Stir in the parsley and season with salt and pepper to taste.
Garnish bowls with reserved dried mushrooms, parmesan, and some parsley. Serve immediately.