Combine the olive oil, garlic, cilantro and 1 teaspoon each of the salt and pepper in a blender.
Puree until smooth.
In a large bowl, mix together the turkey or chicken, egg and cilantro paste.
Add the bread crumbs and mix only until combined.
Roll into small walnut-sized meatballs in the palms of your hands and place on a tray in the refrigerator.
Heat 2 tablespoons of the vegetable oil in a large stockpot over high heat.
Sauté the leeks and carrots with the remaining 2 teaspoons salt and 1/2 teaspoon pepper for 2 to 4 minutes.
Add the cabbage, jalapeños and tomatoes and cook, stirring frequently, until the vegetables are limp, about 3 minutes longer.
Pour in the chicken stock.
Bring to a boil, reduce to a simmer and cook, uncovered, 15 minutes.
Meanwhile, heat the remaining oil in a medium skillet over medium-high heat until nearly smoking.
Add the chilled meatballs in batches, shaking the pan to prevent sticking, and brown on all sides.
Transfer with a slotted spoon to paper towels to drain.
When all the meatballs are browned, transfer to the simmering stock and cook an additional 5 to 10 minutes.
Stir in the vinegar and serve hot.

Variation: For a heartier dish, add a handful or two of rice or small-shaped pasta along with the stock.