To make the masala powder: Grind the bay leaves, cinnamon, cardamom, cloves, fennel seeds and peppercorns in a spice grinder until mixture is a fine powder.
Place the beef cubes, masala powder, 2 cups chopped onion, green chiles, grated fresh ginger, garlic and turmeric in a large, heavy pot. Add water to cover (about 1 cup) and bring to a boil. Reduce heat and simmer for 30 minutes until beef is cooked through. Add salt. Stir and continue to simmer about 10 minutes or until mixture is almost dry, but do not allow it to burn (add a bit more water, if necessary). Set aside.
Heat oil in a large skillet over medium-high heat. Add mustard seeds and cook until they begin to pop. Immediately add remaining 1 cup chopped onion and stir over medium heat until onions soften and begin to brown, about 10 to 12 minutes. Add curry leaves and cook until brown, about 3 minutes.
Stir in the beef mixture, black pepper, and lemon juice. Cook until nicely browned and heated through, about 8 minutes.
