In a 4-quart kettle cook onion in butter over moderate heat, stirring occasionally, until softened. Add corn and sugar and cook, stirring occasionally, for 3 minutes. Add broth and simmer, stirring occasionally for 5 minutes, or until corn is just tender. Add salsa and simmer, covered for 5 minutes. Add the remaining ingredients and cook, uncovered, over moderately high heat until just heated through. Season chowder with salt and pepper and serve with lime wedges.
Recipe courtesy of Gourmet Magazine