If using Rice or Rice Noodles or other types noodles to add on at the end...Go ahead and prepare that separately so it can sit warmed and ready by the time the soup is done.
Heat oil in a big pot or dutch oven over medium-high heat, add lemongrass stalks, ginger, and onions, sear for about 3 minutes. Stirring frequently.
Add curry paste, garlic, peppers, kaffir lime leaves saute for another 1 minute. Stirring frequently.
Add broth, coconut milk, sugar, fish sauce, and chicken, give a good stir to make sure nothing is stuck to the bottom of your pot and to incorporate everything well.
Add chopped Kale and Sweet Potatoes.
Turn up the heat and bring to a full boil then turn the heat down to medium-low and let simmer uncovered for 15-20 minutes.
Check potatoes and a chicken piece for doneness, then add lime juice, stir and taste.
Remove lemongrass stalks and serve either on its own or with rice. Once dished, top with another squirt of lime and chopped Basil (if you have some).