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, or overnight for maximum flavor penetration.
02 - Layer the sliced onions, chopped tomatoes, cubed potatoes, and slit green chilies evenly across the bottom of the slow cooker insert.
03 - Arrange the marinated beef over the vegetable layer, ensuring even distribution.
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 the beef broth and coconut milk into the slow cooker. Gently stir to combine the liquids with the spices and meat without disturbing the vegetable layer excessively.
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 to a rich consistency.
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 chopped fresh cilantro and serve hot with steamed basmati rice or warm naan bread.