How to Make It
Heat the oil in a large skillet over medium heat. Add the onion and 3 cloves of garlic and cook, stirring occasionally, until beginning to brown, 5 to 7 minutes.
Add the tomatoes (with their juices) and chipotles; using a potato masher, break up the tomatoes. Simmer, partially covered, until the sauce has thickened, 15 to 20 minutes. (If the sauce becomes too thick, add up to ½ cup water).
Meanwhile, cook the rice according to the package directions.
.While the rice is cooking, combine the beef, cilantro, bread crumbs, egg, cumin, the remaining 3 cloves of garlic, 1 ½ teaspoons salt, and ¼ teaspoon pepper in a medium bowl. Shape the mixture into 16 meatballs (about 2 heaping tablespoons each).
Heat broiler. Place the meatballs on a foil-lined broilerproof baking sheet and broil, turning once, until cooked through, 8 to 12 minutes.
Add the meatballs to the sauce. Serve over the rice and sprinkle with additional cilantro.