Trim the tops and bottoms of the mushrooms, leaving the stems. Discard the bottoms and save the tops for another recipe. Cut the stems into scallops, about 1 inch thick. You will have 18 to 20 scallops.
Add the scallops to a big bowl and cover with water and wine. Top with another bowl that fits right inside so the liquid is pressed into the mushrooms. Soak for 3 to 4 hours.
Cook the pasta until al dente. Drain, reserving some pasta water, and set aside.
Drain the liquid from the mushrooms. Heat a nonstick skillet and add the olive oil. Add the red pepper flakes and cook for 30 seconds, until fragrant. Add the scallops. Cook for 8 to 10 minutes, until the liquid has evaporated and the scallops are seared. Use tongs to turn them and cook the second side for 2 to 3 minutes. Take out of the pan and set aside.
Add another teaspoon of olive oil into the pan and add the onions. Sauté on medium heat until fragrant and translucent. Add the tomato paste and stir around. Add the crushed tomatoes, white wine, oregano and salt and combine. Simmer until the sauce thickens slightly, about 10 minutes.
Add the scallops back into the tomato mixture and toss to coat. Stir in the fresh parsley, reserving some for garnish.
Add the pasta to the sauce and two tablespoons of the reserved pasta water. Toss together until everything is coated with sauce. Garnish with the remaining parsley. Serve on a big platter and enjoy!