Trim large fat from edges of ribs and season with salt and freshly ground pepper. Melt better in an oven-safe dutch oven pot over medium high heat. Add ribs to pot and brown well on all sides (add ribs in at least two batches to ensure proper browning). Remove browned ribs to a large bowl and set aside.

Add onions to pot and cook until golden, about 5 minutes. Add parsnips and cook until golden, another 5 minutes or so. Add garlic and rosemary, cook until garlic has softened slightly.

Add the bottle of red wine and the beef broth. Bring to a simmer, scraping up the browned bits from the bottom of the pot. Return ribs to the pot, cover, and place into a preheated 325° oven. Braise in the oven for 2 1/2 hours.

Remove pot from oven, and transfer the ribs to a bowl. Check for any loose bones that may have come loose and are drifting in the broth, and remove. Using a slotted spoon, remove most of the parsnip pieces and reserve in a bowl. Ideally place the broth, parsnip pieces and meat in separate containers and refrigerate until the next day. 

When ready to serve, remove the layer of fat from the broth and discard. Take about 1/4 cup of the broth and add to a small blender with the parsnip pieces, blend until smooth. Add parsnip puree into the broth, and bring the broth to a simmer. Mix 1 tablespoon of butter with the flour and blend into a paste. Add to the simmering pot to thicken the broth into a light gravy. Return meaty ribs to the pot and simmer over low heat until they are warmed through. Plate and serve with mashed potatoes.

Fill a large pot with water and add parsnips, potatoes and a generous pinch of salt. Bring to a boil and cook for 15–20 minutes, until the potatoes and parsnips are very soft. Drain.

Meanwhile, in a small bowl or glass measuring cup, microwave milk and butter until the butter has melted and the milk is warm. Add to the cooked, drained potatoes and mash. Test for flavour and add salt if needed. Serve with short ribs and gravy.