In a large bowl, combine masa harina with the warm water. Add the ground meat, ½ teaspoon salt (optional), a generous grinding of black pepper, and one minced garlic clove. Mix these ingredients with your hands and shape into tiny balls, between the size of a large marble and a small walnut. (Mixture makes 40-45 small meatballs.) Set aside.
In small skillet, heat 2 tablespoons lard or vegetable oil over medium-high heat. Add 1 whole garlic clove. Let cook 20-30 seconds to flavor the oil, pressing down with the back of a cooking spoon. Remove and discard garlic. Off the heat, add the flour to hot fat and quickly stir to combine. Cook over medium heat, stirring constantly to smooth out lumps, until mixture is golden (about 1 minute).
Meanwhile, have stock heating in a large (at least 6-quart), deep saucepan or Dutch oven. Just before it boils, add a little hot stock to the browned flour mixture and whisk or stir to eliminate lumps. Pour the mixture into the hot stock and bring to a boil, whisking or stirring with wooden spoon to keep from lumping. Reduce heat to medium-low and simmer stock, uncovered, 5 minutes. It will thicken slightly. Season with a little salt and pepper, being careful not to overseason (meatballs will add more salt).
Make a recaudo: In large skillet, heat another 2 tablespoons lard or vegetable oil over medium-high heat until very hot but not quite smoking. Add the chopped scallion, roasted tomato, roasted chiles, and remaining 2 minced garlic cloves. Reduce heat a little and sauté briskly for 2 minutes, stirring frequently. Add the sautéed mixture to stock. Add chopped cilantro and mint. Simmer uncovered another 5 minutes. Add meatballs. Let stock return to the boil and simmer uncovered over low heat 15 minutes. Correct seasoning.