Marinate lamb in yogurt and set aside for at least two hours.
Heat oil in a pressure cooker, and add cumin, coriander and fennel seeds along with curry leaves, allowing them to sizzle.
Add in onions, ginger and garlic, and saute till lightly brown. Stir in spices and salt, and slowly mix in the marinated lamb along with any remaining marinade.
Add in about a cup of water, close the lid, and cook under pressure for 30 minutes.
Once the pressure has released naturally, slowly open the lid and give it stir to mix everything well. Garnish with cilantro leaves and lemon wedges, and serve warm.