Preheat and Prepare: Preheat your oven to 160°C (320°F). In a large oven-proof pot, heat the olive oil over medium-high heat.
Brown the Shanks: Season the lamb shanks with salt and pepper. Add them to the pot and brown all sides. This should take about 10 minutes. Remove the shanks and set aside.
Sauté the Vegetables: In the same pot, add the onions and garlic. Cook until they are soft, about 5 minutes.
Make the Sauce: Sprinkle flour over the cooked onions and garlic, stirring well to combine. Pour in the red wine and chicken stock, and bring to a simmer while stirring. Add the redcurrant jelly, rosemary, carrots, parsnips, and turnips.
Cook the Lamb: Return the lamb shanks to the pot. The liquid should cover them at least halfway. Bring to a simmer, then cover and transfer to the oven. Cook for about 2 hours, or until the meat is tender and easily separates from the bone.
Finish and Serve: Remove the shanks and vegetables from the sauce. Place the pot over high heat and reduce the sauce to your desired thickness. Whisk in a knob of butter for a glossy finish. Taste and adjust seasoning with salt and pepper. Serve the shanks with the vegetables and sauce.
