In a mortar and pestle, grind the coriander seeds and cumin seeds until fine.
Add the chilies, garlic, shallots, lemongrass, galangal, lime zest, shrimp paste (if using), paprika, and salt.
Pound and grind all the ingredients together until you have a smooth paste. Alternatively, you can use a food processor to make the paste.
Heat a large wok or skillet over medium-high heat and add the vegetable oil.
Add the red curry paste and stir-fry for a couple of minutes until fragrant.
Add the duck pieces and stir-fry for about 3-4 minutes until they start to brown.
Add the sliced red and green bell peppers, and eggplant to the wok. Stir-fry for another 2-3 minutes.
Pour in the coconut milk and add the torn lime leaves (or lime zest).
Reduce the heat to low and simmer for about 10-15 minutes, or until the duck is cooked through and the vegetables are tender.
Season the curry with fish sauce and palm sugar. Adjust the seasoning to your taste by adding more fish sauce for saltiness or palm sugar for sweetness.
Once the duck is tender and the flavors have melded together, remove the curry from the heat.
Serve the Thai Red Duck Curry hot, garnished with fresh Thai basil leaves.Enjoy your delicious Thai Red Duck Curry with steamed jasmine rice!