Heat the oil in a large nonstick skillet over medium-high heat. Season the pork with 1/2 teaspoon salt and a few grinds of pepper; cook until browned, 3 minutes per side. Transfer to a plate.
Add the red onions to the skillet and season with salt. Cook, stirring, until lightly browned, 3 minutes. Reduce the heat to medium, stir in the flour and cook, stirring, 2 minutes. Add the chicken broth and bay leaf. Cook, stirring, until thickened, about 3 minutes. Add the vinegar, then return the pork to the skillet to warm through.
Meanwhile, bring 2 1/4 cups water to a boil in a medium saucepan over medium-high heat. Add the grits and 1/2 teaspoon salt. Reduce the heat to low and cook, stirring, until thickened, 5 minutes. Stir in the cheese.
Remove the pork from the skillet; discard the bay leaf and stir the parsley into the pan sauce. Serve the pork with the grits. Top with the pan sauce and more parsley.
Photograph by Justin Walker
Courtesy of Food Network Magazine