1.For spice paste, process all ingredients in a food processor until a paste forms, adding a little water if necessary.
2.Heat oil in a heavy-based saucepan, add spice paste and stir over medium heat for 5 minutes or until fragrant. Add coconut milk, sugar, stock and mint and, stirring continuously, bring to the boil. As soon as mixture comes to the boil, reduce heat to low and simmer for 15 minutes.
3.Add seafood and cook, covered, just until seafood is cooked through and mussels have opened. Using a slotted spoon, remove seafood and keep warm. Divide noodles, beans and seafood among soup bowls. Ladle hot laksa over, sprinkle with coriander sprigs and serve immediately, with lime wedges passed separately.