Heat the oil in a large saucepan; add curry paste, cook until fragrant. Add ginger and shallots; cook, stirring, until translucent.
Add pumpkin and tomatoes, stir to coat. Add stock, bring to the boil; simmer, uncovered, until the pumpkin is very soft. Blend the soup and return to the same clean pan.
Over a gentle heat, stir in the coconut cream and enough water to achieve the desired consistency. A thinner soup is better for this recipe as it does not overwhelm the crab – you are looking for the consistency of pouring cream. Stir until soup is hot.
Season the soup with fish sauce and lime juice to taste; do not boil. Divide among 6 warmed soup bowls.
Top each serving with some of the crab meat, the chilli, coriander and fried shallots.
Soup suitable to freeze and microwave.
Cook's note: Fried shallots are available from the Asian section of most supermarkets and Asian food stores. This soup is medium in chilli heat; omit the chillies for a milder soup.
Photographer: Ian Wallace Stylist: Yael Grinham