Blend 4 tablespoons water, garlic, and ginger into a smooth paste in a blender.

Heat oil in a wide, heavy pot over medium heat. Cook lamb in batches until browned, about 5 minutes per batch. Transfer to a bowl.

Combine cinnamon sticks, cardamom, peppercorns, cloves, and bay leaves in the same pot. Stir once and cook until cloves swell and bay leaves change color, 2 to 3 minutes. Add onions. Cook and stir until browned, about 5 minutes. Add the ginger-garlic paste; stir for 30 seconds. Add paprika, cumin, coriander, cayenne, and salt. Cook until fragrant, about 30 seconds.

Stir the browned lamb and its juices into the pot. Stir for 30 seconds. Add yogurt, 1 tablespoon at a time, blending well after each addition. Cook and stir for 3 minutes more. Pour in 1 1/2 cups water; bring to a boil, scraping browned bits off the sides and bottom of the pot. Cover and reduce heat to low. Simmer until meat is tender, about 1 hour, stirring well every 10 minutes.

Uncover pot, increase heat to medium, and reduce some of the liquid if desired. Spoon accumulated fat from the surface of the mixture. Mix in garam masala and black pepper before serving.