Heat 2 tablespoons butter in a large nonstick skillet over medium-high heat. Add the bell pepper and onion and cook, stirring occasionally, until the vegetables are softened and lightly browned, 8 to 10 minutes. Add the garlic, Cajun seasoning and pork and continue to cook, stirring, until the garlic is softened and the pork is warmed through, about 2 minutes.
Push the pork mixture to one side of the skillet and add the tomato paste to the other side. Cook, stirring, until dark red, about 1 minute. Add the chicken broth and Worcestershire sauce and simmer, stirring everything together, until the sauce is slightly thickened, 2 to 3 minutes. Season with salt, pepper and hot sauce.
Meanwhile, bring 3 cups water to a simmer in a medium saucepan over high heat. Slowly whisk in the grits, 1 teaspoon salt and 1/2 teaspoon pepper. Reduce the heat to medium low and cook, stirring occasionally, until thickened, about 5 minutes. Stir in the remaining 2 tablespoons butter and the scallions.
Divide the grits among shallow bowls and top with the pork mixture and sauce. Sprinkle with parsley and serve with more hot sauce.