Heat the oven to 425°F with a rack in the middle position. In a 9-by-13-inch baking dish, toss together the tomatoes, smashed garlic, oil, chipotle chilies OR 1 tablespoon harissa, ¼ teaspoon each salt and pepper and ¼ cup water. Bake, uncovered, until the tomatoes have broken down, 30 to 35 minutes; stir once about halfway through.
Meanwhile, in a medium bowl, combine the panko and ½ cup water. Let stand until the panko softens, about 5 minutes, then use your hands to mash to a smooth paste. Add the beef, grated garlic, adobo sauce OR 2 teaspoons harissa and ½ teaspoon each salt and pepper; mix thoroughly with your hands. Divide into 12 portions, rolling them into smooth balls. Place on a large plate and refrigerate until ready to use.
Remove the baking dish from the oven and nestle the meatballs in the tomato sauce. Bake, uncovered, until the meatballs are browned and the centers reach 160°F, about 15 minutes. Taste and season the sauce with salt and pepper. Sprinkle with cilantro.
