In a bowl, combine the beef, cinnamon, coriander, turmeric, cayenne, salt, pepper, and half of the garlic. With clean hands, mix thoroughly, then shape the meat into 3/4-inch meatballs. Set aside and let sit for 30 - 90 minutes to allow flavours to meld.
In a large, heavy pan, heat the oil, add the onion, and cook over low heat for 10 to 15 minutes or until it is very soft. Turn the heat to medium-high and add the meatballs. Cook, turning them often, until they lose their pink color.
Add the plum tomatoes and remaining garlic. Cover the pan, turn down the heat, and simmer gently for 10 minutes. Add the sun-dried tomatoes, salt, and pepper and cook the mixture for 5 minutes over low heat, stirring once or twice.
For the noodles:
Bring a large saucepan of water to a boil. Add the noodles and cook for 2 to 4 minutes or until they are tender but still have some bite. Drain the noodles and transfer them to a bowl. Stir in the kefir, garlic, and salt. Toss thoroughly and transfer to 6 wide bowls. Spoon meatballs around the edges of each bowl of noodles, add the mint to the center and serve at once.