Preparation Cook onion, garlic, and spices in oil in a 5- to 6-quart heavy pot over moderately low heat, stirring, until onion is softened, about 6 minutes. Stir in vinegar and simmer 1 minute. Add chickpeas, sugar, and tomatoes with their juice, then increase heat to moderate and gently simmer, uncovered, stirring occasionally, until slightly thickened, about 15 minutes. Add mussels and return to a simmer. Cover tightly with lid and cook until mussels just open wide, 3 to 6 minutes. (Discard any mussels that remain unopened after 6 minutes.) Stir in parsley and serve in shallow bowls.
Preparation Cook onion, garlic, and spices in oil in a 5- to 6-quart heavy pot over moderately low heat, stirring, until onion is softened, about 6 minutes. Stir in vinegar and simmer 1 minute. Add chickpeas, sugar, and tomatoes with their juice, then increase heat to moderate and gently simmer, uncovered, stirring occasionally, until slightly thickened, about 15 minutes. Add mussels and return to a simmer. Cover tightly with lid and cook until mussels just open wide, 3 to 6 minutes. (Discard any mussels that remain unopened after 6 minutes.) Stir in parsley and serve in shallow bowls.