Heat the oil in a medium skillet over medium heat. Add the curry paste and cook for a couple of minutes until very fragrant and starting to sizzle. Whisk in the stock and bring the mixture to a boil. Whisk in the coconut milk and cook until just starting to simmer. Mix in the lemon juice, lower the heat, and keep warm. You can make the curry soup up until this point a day in advance and store in the fridge until ready to use.
Cook the pasta in salted boiling water until al dente. Drain and return to the pot. Add a spoonful of the curry soup to moisten the noodles and prevent them from sticking together. Add the cooked lobster and toss to heat slightly. You can reserve some lobster meat to place on top of the noodles for presentation.
Divide the noodles between four small bowls. Arrange any reserved lobster meat on top. Sprinkle the cilantro and peanuts on top. Pour the soup around the noodles in each bowl. I like to put the soup into a separate jug and pour it into the bowls at the table in front of my guests.