In a large pot of boiling water, cook noodles until just tender, about 2-3 minutes. Rinse under cold water and drain; set aside.
Add the butter into a small saucepan and heat over medium-low heat until melted. Add the tomato paste, ginger, garlic, shallot and curry paste. Stir to release the fragrance, 1 minute or so.
Add the apple and coconut milk. Bring to a boil over medium heat.
Add the broth. Let cook until boiling again.
Add the bok choy. Simmer for 2 to 3 minutes, until the noodles are cooked through. Immediately transfer everything to a serving bowl.
Warm the sliced ham by dripping into the hot broth.
Divide noodles and broth into bowls. Top with sliced ham, soft-boiled eggs, cilantro, scallion, chili oil and sesame seeds.
For the Soft-boiled Egg
Bring a small pot of water to a boil. Turn to medium-low heat and slowly lower the egg into the pan using a ladle. Simmer for 5 to 6 minutes for a soft-boiled egg.