Heat the oil in a large pan over medium heat.
Add mustard, fennel, nigella, fenugreek, and cumin seeds. Let them crackle for 30 seconds until aromatic.
Add the onions and sauté until golden brown.
Stir in ginger and garlic pastes; cook for 1–2 minutes.
Add beef pieces and cook until browned on all sides.
Mix in tomatoes, chilli powder, turmeric, coriander powder, and salt. Cook until oil separates.
Pour in yoghurt and stir well to coat the beef.
Add water, cover, and cook on low heat for 1 hour or until beef is tender.
Once cooked, sprinkle garam masala, lemon juice, and add green chillies.
Simmer uncovered for 5 minutes to thicken the gravy.
Garnish with chopped coriander before serving.
