In a large bowl, combine the lamb, beef and oregano; season with salt and pepper. Shape into 1/2-inch meatballs.
In a large saucepan, heat the olive oil over low heat. Add the garlic and 1 tablespoon water and cook, stirring frequently, until translucent but not brown, 6 to 8 minutes. Add 3 cups water and bring to a boil over medium-high heat. Lower the heat and simmer for 5 minutes. Add the meatballs, cover and simmer for 10 minutes. Stir in the kale, cover and cook until tender, about 10 minutes. Season with salt and pepper. Serve the meatballs and kale in shallow bowls with enough broth to moisten.