01 - Combine beef cubes with yogurt, lemon juice, ginger-garlic paste, salt, turmeric, coriander, and chili powder in a large bowl. Toss thoroughly to coat all pieces. Cover and refrigerate for at least 30 minutes, preferably overnight for maximum flavor penetration.
02 - Arrange sliced onions, chopped tomatoes, cubed potatoes, and slit green chilies evenly across the bottom of the slow cooker insert.
03 - Place the marinated beef on top of the vegetable layer, allowing any excess marinade to drip into the cooker.
04 - Sprinkle curry powder or garam masala, ground cumin, smoked paprika, bay leaves, cinnamon stick, whole cloves, and cardamom pods evenly over the beef.
05 - Pour beef broth and coconut milk into the slow cooker. Gently stir to distribute spices without disturbing the layered arrangement.
06 - Cover and cook on LOW setting for 8 hours or HIGH for 4 hours. The beef should be fork-tender and the sauce thickened and deeply aromatic.
07 - Fish out and discard bay leaves, cinnamon stick, cloves, and cardamom pods before serving.
08 - Taste the curry and adjust seasoning with additional salt and pepper as desired. Garnish generously with fresh cilantro and serve hot alongside steamed basmati rice or warm naan bread.