In a large pot over medium heat, warm the oil. Add the onion and salt and cook for 3-5 minutes, or until softened. Add in the garlic and cook for another minute, stirring often.
Add the ginger, lemongrass, water, and soy sauce. Cover and increase the heat to high to bring to a boil. Add the chicken and long cooking veggies (see note). Cover and let it come back to a boil. Reduce the heat to low or medium-low to maintain a simmer for 10-15 minutes (depending on size of chicken), or until chicken is cooked through, stirring halfway. Add in any remaining quick cooking veggies in the last 3-5 minutes of cook time.
Turn off the heat and remove the chicken. Stir in the kale (if using), coconut milk, lime, and fish sauce. Shred the chicken and stir it back in. Taste and add more lime or salt if it tastes like it still needs something.
Serve topped with fresh cilantro. If you want to add a little kick, stir some sriracha into your bowl.