In a saucepan, melt 2 tablespoons of butter over medium heat. Add the onion and garlic to the pan. Cook until softened, about 5 minutes. Add the tomato paste and cook for two to three minutes, or until golden. Add the orzo, stir to combine and cook for 2 minutes. Deglaze the pan with 1 1/2 cups of chicken stock. Let the pasta cook while the stock thickens and reduces. Stir frequently. Once the stock reduces by half add another ladleful of stock to the orzo. Stir frequently. Continue this process until the orzo is thoroughly cooked, about 30 minutes.
Meanwhile, in a medium-sized bowl, combine the shrimp, 1 teaspoon of kosher salt, oregano and black pepper. Set aside.
The last 6 to 8 minutes of cooking, add the cream, seasoned shrimp and red pepper flakes. Stir and let simmer for six minutes. Add the remaining 2 tablespoons of butter, 1 teaspoon of kosher salt, parmesan cheese, red wine vinegar and a final ladleful of stock. Stir, taste and season.
Top with freshly chopped basil and serve warm.