Stir the cider, sugar, and vanilla extract in the insert set in a 5-, 6-, or 8-quart Instant Pot until the sugar dissolves. Push the “stem” ends of the cloves into the orange and drop it into the pot. Add the cinnamon stick, too. Nestle the pear halves into this liquid and lock the lid on the pot.
For the MAX model: Set the pot for pressure cook and set the level to MAX. Set time for 3 minutes with the Keep Warm Setting off. For all other models: Set the pot for Pressure Cook or Manual and set the level to High Pressure. The valve must be closed and the Keep Warm setting off. Set the time for 4 minutes with the Keep Warm setting off. For the Slow-Cook function: Set the pot for Slow Cook and set the level to High. The Valve must be open. Set the time for 2 hours with the Keep Warm setting off.
When the pot has finished cooking under pressure, turn it off and let the pressure return to normal Naturally, about 25 minutes. Whichever cooking method you’ve used, unlatch the pot and open the cooker. Use a slotted spoon to transfer the pear halves to a heat- safe, glass, or other non-reactive storage bowl (do not use plastic). Remove and discard the orange, any cloves that have fallen out, and the cinnamon stick.
Set the Instant Pot for Saute and set it for High or More. Set the time for 10 minutes.
Stir constantly as the sauce comes to a simmer. Continue cooking, stirring almost constantly, until the sauce has reduced to a thick syrup, about half the volume it was after you removed the pears, about 10 minutes. Turn off the heat and pour this hot syrup over the pears. Cool to room temperature, about 45 minutes, before serving. Or cool to room temperature, cover, and store in the refrigerator for up to 4 days (when you can serve them cold or let them come back to room temperature).