Roughly crush the cinnamon, cardamom, black peppercorns and fennel seeds with a mortar and pestle and keep aside.
Set the Instant Pot to SAUTE mode. Once it turns HOT, pour the oil into the pot liner. Add the crushed spices, onion, garlic and ginger. Saute till the onion softens and starts browning.
Move around the onion mix to make space for the meat and add the lamb cubes to the Instant Pot. Make sure most all of them are touching the bottom of the pan, so get a nice sear. After a couple of minutes, slowly turn the pieces so the other side of the meat can sear as well.
Once done, add a little water, about ¼ cup and deglaze the pot. This is to make sure that the burnt bottom does not get even more burnt while pressure cooking is in progress or it will give a BURN notice on the Instant Pot.
Add the tomatoes, salt, turmeric powder, coriander powder and meat masala powder. Mix well.
Hit CANCEL / KEEP WARM button to get off SAUTE mode.
Set to MANUAL / PRESSURE COOK mode and adjust the time to 30 mins. Close the lid and seal the Instant Pot.
Once the pressure cooking is done, wait for the pressure to be released naturally. Watch for the little silver button next to the seal to go down. Move the seal knob to release and slowly open the Instant Pot.
The curry may seem a little watery, give it a quick mix to get all the onion mixture and meat to combine. If it still looks watery or you want it thicker, you can add some coconut milk or cook it in SAUTE mode for a few more minutes.
Garnish with cilantro and serve hot.
If you are unable to find Curry Masala powder, use Garam Masala. Do not use Curry Powder, it just wont be the same.