Place lemongrass on slow cooker, then top them with chicken. Add kafir lime leaves
In food processor, mix onion, tomatoes, chilies and the rest of the ingredients, except water and basils
Pour paste onto pan and saute until fragrant and bubbly, then pour paste into slow cooker, season with salt and white pepper to taste. Add in water if not broth. Cook chicken on low setting for 6-8 H (or high for 5-7 H)
30 minutes before turning off the slow cooker, add basils and continue cooking