Cut chicken thighs into 2-3" pieces. If using drumsticks, keep them whole. Season the chicken with salt and set aside.
Heat a large pot or Dutch oven over medium high heat and add a couple of tablespoons of oil.
Add the potatoes and brown on all sides. Do this in batches to avoid overcrowding and set aside.
Add a bit more oil, just enough to coat the bottom. Add chicken and brown on both sides. Do this in batches as well.
Return the chicken to the pot and add diced onions. Sauté until slightly translucent.
Stir in the curry powder and let it fry in the oil for about a minute to draw out the flavor.
Add potatoes, carrots, lemongrass and bay leaves.
Pour in the chicken stock and enough water to cover the ingredients.
Bring to a boil. Cover and simmer over medium/low heat for about 20 minutes or until the potatoes are fork tender. Your cook time may vary depending on the size of your potatoes.
Remove the lemongrass and bay leaves. Add coconut milk, fish sauce and sugar.
Season with salt to taste. The amount you need will vary depending on how much salt is in your chicken stock. Start with a teaspoon.
If you prefer a thicker curry, stir in cornstarch slurry. Mix together cornstarch and water and stir in about half of the slurry to start. Let the curry return to a boil. If it needs to be thicker, repeat the steps with cornstarch slurry.
Serve Vietnamese Chicken Curry with crusty baguettes, rice vermicelli or steamed rice.
Notes
I prefer my Vietnamese Chicken Curry to be slightly thickened. Not as thick as Japanese curry, but not soupy either. After cooking, I thicken the curry broth a bit with cornstarch slurry. Mix equal parts cornstarch and cold water. After seasoning the curry, slowly drizzle a tablespoon of cornstarch slurry into the simmering broth. Stir the slurry in well, being careful not to break the potatoes, and allow the Ca Ri Ga to return to a boil. Repeat with the cornstarch slurry a tablespoon at a time until you reach your ideal consistency.