Marinade the lamb pieces with yogurt and turmeric powder, and let it sit for at least half an hour.
Set the Instant-Pot to saute mode, and add in the oil to heat. Add in the panch phoron and let them start to sizzle.
Add in and saute the onions, ginger and garlic, stirring occasionally, till they begin to soften and turn slightly brown. Mix in the spices, salt and tomato paste, and fry for a minute or two to blend well.
Add in the tomatoes and cook for a couple of minutes till they start to soften and pulp.
Slowly stir in the lamb with all the leftover marinade and add in enough water to cover the meat. Put on the lid and set the Instant-Pot to Manual Pressure mode, and make sure that the valve is in the sealing position. Set the pressure timer to 25 minutes and let it cook.
Once the timer goes off, let the pressure release naturally, then give it a final stir and garnish with fresh cilantro leaves and some lemon juice. Serve hot.