Step 1

Arrange a rack in the middle of the oven and heat to 300°F. Rinse the dried mushrooms lightly to remove any dust or grit. Place the mushrooms in a heatproof bowl and pour the boiling water over them. Set aside to steep while you cook the onions.

Step 2

Chop 1 of the onions into a fine dice. Heat 2 tablespoons of the olive oil in a 3-quart (or larger) ovenproof pot or Dutch oven over medium heat. Add the diced onion and garlic and cook, stirring occasionally, until soft and golden, about 8 minutes. Push the onions to the side of the pot, and turn the heat up to medium-high. Add the cremini mushrooms and cook for 5 minutes without stirring. Flip the mushrooms and cook until they are quite brown and a crust is developing on the bottom of the pan, about 5 minutes more.

Step 3

Drain the dried mushrooms, reserving the liquid. Add the dried mushrooms and rosemary sprig to the pan and sauté briefly. Add the rice and cook, stirring once or twice, until it begins to turn transparent, about 4 minutes.

Step 4

Turn the heat to high and add the white wine, vinegar, broth, and reserved mushroom steeping liquid. Stir and scrape the bottom of the pan as you add the liquid to deglaze any yummy mushroomy bits sticking to the pan. Stir in the salt and pepper.

Step 5

Bring to a boil. Cover the pan with a tight-fitting lid and put it in the oven to bake for 35 minutes.

Step 6

While the rice is baking, make the caramelized onions. Thinly slice the remaining 3 onions. Heat the remaining olive oil in a cast iron skillet over medium heat until shimmering. Add the onions and sprinkle generously with salt. Reduce the heat to low and cook, stirring occasionally, until the onions turn a dark mahogany brown. Let them go as long as you can; I usually cook mine for at least 30 minutes.

Step 7

When the risotto has finished baking, remove the rosemary sprig, stir, and let it stand uncovered for 5 minutes before serving. Dish it up and top each bowl with a spoonful of caramelized onions, a little extra pepper, and, if desired, a scoop of sour cream, whipped mascarpone, or whipped Tofutti Better Than Cream Cheese.