01 - Combine beef with yogurt, lemon juice, ginger-garlic paste, salt, turmeric, coriander, and chili powder in a large bowl. Toss thoroughly to coat. Cover and refrigerate for at least 30 minutes, preferably overnight for maximum flavor penetration.
02 - Layer the sliced onions, chopped tomatoes, cubed potatoes, and green chilies at the bottom of the slow cooker insert.
03 - Arrange the marinated beef cubes evenly over the vegetable layer.
04 - Sprinkle curry powder or garam masala, ground cumin, smoked paprika, bay leaves, cinnamon stick, whole cloves, and cardamom pods over the beef.
05 - Pour in the beef broth and coconut milk. Gently stir to distribute the spices and liquids throughout the mixture.
06 - Cover and cook on LOW setting for 8 hours or HIGH for 4 hours. The beef is done when it's fork-tender and the sauce has thickened considerably.
07 - Discard the bay leaves, cinnamon stick, cloves, and cardamom pods before serving.
08 - Taste the curry and adjust seasoning with additional salt and pepper as needed. Garnish generously with fresh chopped cilantro. Serve hot accompanied by steamed basmati rice or warm naan bread.