In a dry skillet over medium heat, add the coriander seeds and cumin seeds. Toast them for about 2-3 minutes until they become fragrant. Be careful not to burn them. Once toasted, remove from heat and let them cool slightly before grinding them into a powder using a spice grinder or mortar and pestle.
In a large skillet or Dutch oven, heat the olive oil and butter over medium heat. Add the chopped onion and sauté until it becomes translucent and golden, about 5-7 minutes. Stir in the minced garlic, chopped ginger, and jalapeños, cooking for an additional 2 minutes until fragrant.
Add the ground coriander, ground cumin, ground turmeric, cayenne pepper, curry powder, bay leaves, and star anise to the onion mixture. Stir well to coat the onions and allow the spices to bloom for about 1-2 minutes.
Add the chicken thighs to the skillet, stirring to coat them in the spice mixture. Cook until the chicken is browned on all sides, about 5-7 minutes.
Add the chopped tomatoes to the skillet, mixing them into the chicken and spices. Pour in the coconut milk and bring the mixture to a gentle simmer. Season with kosher salt and black pepper to taste.
Reduce the heat to low, cover the skillet, and let the curry simmer for about 20-25 minutes. This allows the chicken to become tender and the flavors to meld together beautifully.
Once the chicken is cooked through, stir in the lemon juice. Taste and adjust the seasoning if necessary. Discard the bay leaves and star anise before serving.
Serve the Authentic Chicken Curry over prepared Basmati rice. Top with chopped cashews and fresh cilantro for added texture and flavor.