Preheat oven to 350°F.

Heat the vegetable oil over medium-high heat in a large dutch oven or stock pot. Add the short ribs and brown them on all sides. Remove the ribs from the pot and set aside.

Reduce the heat to medium, add the diced carrots, celery, and onion. Cook for about ten minutes until the vegetables have softened. Add the garlic and cook for another couple of minutes.

Stir in the tomato paste and then sprinkle in the flour, stirring to coat all the vegetables. Cook for another few minutes.

Pour in the wine and increase the heat until the pot begins to simmer. Scrape the bottom to deglaze the pot.

Add the tomatoes and all their juice, pour in 2 cups of water, and stir. Use a wooden spoon to break up the tomatoes.

Return the short ribs to the pot, ensuring they are covered by the liquid. Add the parsley and stir.

Bring to a strong simmer, cover, and transfer to the preheated oven. Let simmer for 2 to 3 hours until the beef is fork-tender.

Once tender, remove the pot from the oven and the short ribs from the pot. Strain the liquid into a large sauce pot, pressing on solids to extract all liquid.

Bring the sauce to a simmer over medium-high heat and reduce for about 30 minutes while skimming the surface to remove fat.

Shred the short ribs and once the sauce is thickened, add the shredded meat and stir.

Fill a large pot with water and bring to a boil. Add the potatoes and boil until fork-tender. Drain and return them to the cooking pot.

Add the butter to the potatoes and mash with a potato masher. Stir in the sour cream and Parmesan cheese. Season with salt and pepper.

Serve the ragu over the parmesan mashed potatoes and garnish with chopped parsley.