Step 1

In a 12-inch skillet over medium-high, heat the oil until barely smoking. Add the tomatoes, onion and garlic, then cook, occasionally turning the vegetables, until deeply charred in spots, about 5 minutes; if the garlic is done before the tomatoes and onion, remove the cloves from the skillet.

Step 2

Add the charred vegetables to a blender along with the chipotle chilies, chili powder, oregano and 1/2 teaspoon salt; set the skillet aside. Blend until the mixture is smooth, about 1 minute, scraping the blender jar as needed. Measure ⅓ cup of the puree into a medium bowl, mix in the panko and let stand until fully softened, about 5 minutes. Pour the remaining puree into the reserved skillet and set aside.

Step 3

Line a rimmed baking sheet with kitchen parchment. To the panko mixture, add the egg yolk, both ground meats, 3/4 teaspoons salt and ¾ teaspoon pepper. Using your hands, mix until homogenous. Divide into 12 portions (about ¼ cup each) and place on the prepared baking sheet. One portion at a time, in the palm of your hand, flatten into a 3- to 4-inch disk. Place a wedge of hard-cooked egg in the center, then enclose meat around the egg and roll between your palms to form a smooth ball. Set the meatball on the prepared baking sheet and repeat with remaining ingredients. Refrigerate uncovered for 10 minutes.

Step 4

Meanwhile, set the skillet over medium and bring the sauce to a simmer. Reduce to medium-low and cook, stirring occasionally, until slightly thickened and darkened, about 10 minutes. Place the meatballs in the skillet, then cover and cook at a gentle simmer until the centers reach 160°F, 15 to 20 minutes; turn the meatballs once about halfway through. Serve sprinkled with cilantro and chicharrón (if using).