Heat the oil in a medium saucepan over medium heat. Add the onion, garlic, chipotle, chili powder, and salt and cook until the onion softens, about 5 minutes. Add the chicken broth, bring to a boil, reduce the heat slightly, and simmer, uncovered, for 10 minutes. Add the corn and cook for 5 minutes more.
Pull the saucepan from the heat and stir in the tomato, chicken, cilantro and lime juice. Divide the tortilla chips among 4 warmed bowls, ladle the soup on top, and serve with lime wedges if using.
Get every last drop of juice from those little limes. Before halving, microwave them for a few seconds and roll them under the palm of your hand to release the juice from the pulp.
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