Place the stainless steel inner pot inside the Instant Pot®. Press Saute and set time to 10 Minutes. Add the olive oil and onion, stirring occasionally. When done, press Cancel.
Add the wine, honey and ½ tsp of salt. Press Saltear and set time to 5 Minutes, stirring frequently. When the time is up, press Cancel and transfer the caramelized onions to another container. Set aside.
Return the stainless steel inner pot to the Instant Pot® (it is not necessary to wash it beforehand). Add whole sweet potatoes and cover with water.
Close and lock the Instant Pot® lid. Make sure the steam release handle is turned to Sealing. Press Pressure Cook, pressure level High, and set time to 20 Minutes.
Once the time is up, press Cancel and turn the steam release handle to Venting. Once all the pressure has been released, open the lid and drain the sweet potatoes.
Return the stainless steel inner pot to the Instant Pot®, press Keep Warm, add the sweet potatoes, and mash them with a fork. Add the honey caramelized onions, butter, plain yogurt, garlic powder (optional), salt and pepper to taste, and mix well. Sprinkle with chives and serve immediately.
Refrigerate in an airtight container for up to 4 days.