Prepare the potatoes and place in a steamer basket which fits your Instant Pot.
Add the oil to the Inner Pot and press Sauté. When hot, sear the sausages and be sure to roll them around to get them brown.
Stir in the sticky onions, wine and water. Place a long legged trivet in then the potatoes in their basket on top.
Put the lid on, set the vent to Sealing and set the pot to Manual High for 8 minutes.
QPR when alarm sounds and remove the potatoes carefully with an oven mitt. Tip into a bowl, mash and add the milk, mustard, butter and cheese. Taste and adjust the seasonings to your preference.
Meanwhile, slake the cornflour in the 1 tbsp of water and pour into the inner pot with the sausages. Turn it back onto Sauté and quickly, the sauce/gravy will start to thicken.
Dish up the mash and serve the sausages and onion gravy on top.
