Preheat the oven to 350. Mix the meat, tortilla chips, egg, chopped cilantro, 1/4 cup scallions, minced garlic, 1 teaspoon chili power, 1 teaspoon cumin, and salt to taste in a bowl. Roll into 16 small meatballs.
Heat the olive oil in a nonstick skillet over medium heat. Add the meatballs and lightly brown, turning as needed, about 5 minutes. Add the smashed garlic and the remaining 2 teaspoons chili powder and 1 teaspoon cumin; cook for 1 to 2 minutes. Add the tomatoes, cilantro sprigs and 1 1/2 cups water and season with salt. Bring to a simmer, then cover, reduce the heat to low and cook until the sauce thickens and the meatballs are tender, about 15 minutes.
About 5 minutes before the meatballs are done, toast the rolls in the oven. Place 2 roll halves in each of 4 shallow bowls and top with 4 meatballs. Drizzle with sauce, then pour the remaining sauce into the bowls. Top with avocado, cheese and/or scallions, if desired.
Photograph by Antonis Achilleos
Courtesy of Food Network Magazine