Combine fish sauce, garam masala, paprika, and turmeric in a bowl. Rub mixture deeply into chicken and let marinate at room temperature for 20 minutes.

Combine onions, habanero pepper, ginger root, and garlic in a blender and process until smooth.

Heat oil in a saucepan over medium heat. Add onion mixture, lemongrass, and shrimp paste. Stir and fry for about 8 minutes.

Pour chicken and marinade into the saucepan. Stir and fry until seared on all sides, about 10 minutes. Add potatoes and salt and stir for about 3 minutes. Add broth, making sure chicken and potatoes are covered; add more liquid if necessary. Bring to a boil and cook, covered, for 20 minutes. Remove lid and cook 10 minutes more.