Prepare the Ingredients: Wash the apples and orange thoroughly. Cut them into quarters, leaving the skin and seeds intact. This will add more flavor to the cider.

Add to the Instant Pot: Place the apple and orange quarters in the Instant Pot. Add the cinnamon sticks, cloves, allspice berries, and brown sugar. Pour in the water, ensuring it covers the fruit and spices.

Cook the Cider: Close the Instant Pot lid and set the valve to the sealing position. Select the "Manual" or "Pressure Cook" setting and cook on high pressure for 15 minutes. Once the cooking cycle is complete, allow the pressure to release naturally for about 20 minutes.

Strain the Cider: Carefully open the Instant Pot and use a potato masher to mash the fruit, releasing more flavor into the liquid. Strain the mixture through a fine-mesh sieve or cheesecloth into a large bowl, pressing down on the solids to extract as much liquid as possible.

Serve and Enjoy: Pour the warm apple cider into mugs and serve immediately. Garnish with additional cinnamon sticks or apple slices if desired. Store any leftover cider in the refrigerator for up to a week.