1. Puree the garlic and tomatoes in a blender until smooth. Heat the olive oil in a large stockpot over low heat. Add the onion, salt and pepper and cook, stirring frequently, until pale brown and caramelized, about 10 minutes. Stir in the tomato puree and cook 10 minutes longer, stirring frequently.
2. Pour in the chicken stock and add the chipotle chile (if desired). Bring to a boil, reduce to a simmer, and cook, uncovered, for 20 minutes. Stir in the tortilla chips and cook 10 minutes longer, until the chips soften. Remove and discard the chile. Serve hot, with cilantro, avocado, Crema, lime wedges and some extra crisp, fried tortilla chips for adding at the table.Serving Size: about 1 cup