In a pot over medium heat, add stock and coconut milk. Bring to a gentle simmer (do not boil hard).
Add onion, garlic, lemongrass, galangal, and makrut lime leaves. Simmer 8–10 minutes to release flavor.
Stir in palm sugar and fish sauce until dissolved.
Add mushrooms, squash, eggplant, and tomatoes. Simmer 5–7 minutes until tender.
Add chicken and cook 5–7 minutes until fully cooked. If using shrimp, cook only 2–3 minutes until pink.
Turn off heat and stir in fresh lime juice. Taste and adjust more fish sauce for salt, more lime for brightness, more sugar to balance.
