Press Saute on the Instant Pot at More heat setting. Wait for it to alert HOT and drizzle the oil in the inner pot.
Season the beef cubes with salt and pepper and add to the Instant Pot. Let the beef brown. Lower the heat to Normal setting. Next, saute the garlic and onions until soft. Stir in the tomato paste to cook and coat the meat.
Pour beef stock, peanut butter, and lemon grass in the Instant Pot. Stir well to dissolve the peanut butter.
Close the lid and turn the valve to Sealing. Set the Instant Pot to Meat/Stew at Normal.
Quick Release pressure when done and open the lid. Stir in the coconut cream.
Serve and squeeze calamansi juice to finish (optional).