Preheat the oven to 350 degrees F.
In a small bowl, add all the spice mix ingredients and mix to combine.
Pat the lamb shanks dry and season with the spice mix on all sides.
In a large Dutch oven pot, heat the olive oil over medium-high heat. Brown the lamb shanks on all sides (about 8 mins or so). Transfer the lamb shanks to a large tray.
Next, add the onions, celery and carrots. Saute for 5-7 minutes on medium-high, or until the vegetables gain some color. Add red wine and scrape the bottom. Reduce the wine by half.
Add the broth, tomatoes, cinnamon stick, thyme, and rosemary. Sprinkle a little salt and pepper. Return lamb shanks back to the pot; press down to submerge. Boil for 40 minutes. Turn heat off.
Cover the pot and transfer to the 350 degree oven. Cook in the oven for 2 1/2 hours. Let the shanks rest for 5 minutes.
Serve the lamb shanks over mashed potatoes.