1. Peel the melons, remove seeds and cut into chunks.
2. Rinse apricot kernels and drain.
3. Thaw frozen whelk if used, then scrub and rinse the whelk clean. Rinse and cut shank of pork into chunks.
4. Bring 1/2 wok of water to the boil, blanch shank of pork and whelk separately, rinse well.
5. In a pot, bring 16 cups of water to the boil, add ginger and apricot kernels, transfer lean pork and whelk to the pot, bring water back to the boil, cover and lower the heat to medium, cook for 2 hours.
6. Add melon chunks to the soup and continue cooking for 20 minutes.
7. When soup is well-flavoured, season with enough salt and serve.