Preheat oven to 375 degrees F.
Dice the cebolla and set aside.
Mince the ajo and set aside.
In the medium bowl, combine the ground beef, ajo, cebolla, cumin, salt, pepper and huevo. Cut the limas in half and squeeze their juice into the bowl. Mix well with spatula, then form into 1- to 1½-inch balls (about 15 meatballs).
On the nonstick baking sheet, cook the meatballs in the oven for about 10 minutes, or until browned. Remove from oven and set aside.
While the meatballs are cooking, cut the zanahorias into thin slices.
In the large soup pot, heat the tomates (with their juice), zanahorias, chicken stock and bay leaf over a medium-high heat and bring to a boil.
When the meatballs are out of the oven, transfer them from the baking sheet into the large soup pot.
Reduce the heat and allow the soup to simmer for 20 minutes before serving.