Cook the udon noodles according to the instructions on the package. Drain and set aside.
In a pan, combine red curry paste, peanut butter, garlic, and ginger. Turn on medium heat and mix the spice paste for 30 seconds to warm it. Add the coconut milk, stock, lemongrass, fish sauce, and lime juice. Mix well and bring to a boil. Cover, reduce the heat to low, and cook for 10 minutes for the flavors to develop.
Make the Eggs: Bring water to a boil, then reduce to a simmer. Add the eggs and cook for 7 ½ minutes. Plunge into iced water and let cool for 3 minutes. Peel and cut in half.
Increase the heat of the soup to a gentle bubble and add the frozen dumplings.
. Cover and cook for 5 - 6 minutes or until they float. Add the udon noodles; cover and cook for 2 - 3 minutes until they have separated.
To serve, divide the noodles, dumplings, and soup between bowls. Top with beansprouts, coriander, and halved eggs. Sprinkle over black sesame seeds and chili oil.
Make the Mango Lassi: In a blender, add mangoes, yogurt, milk, cardamom powder, and sugar. Blend until super smooth. Adjust sweetness and consistency by adding more sugar or milk, or additional mango and a splash of water if desired. Pour into glasses.
Serve the creamy coconut noodle soup with mango lassi.