Drizzle in milk or cream mashing/whipping as you go until you've reached your desired consistency.
Add in salt and mix through. If using pepper, add it in now.
Mix in butter until well combined and taste.
Adjust seasonings as needed. Remember, diners can add more salt to their own servings as some people do not like a lot of salt, so make sure not to over season.
Top with chives for nice color and a bit of an onion flavor.
Russet potatoes are best cooked using the steam method. When boiled in water, they tend to fall a part and become gummy and not pleasant to mash.Yukon Gold potatoes are more versatile and can be boiled or steamed, so if you want to cook potatoes in the pot and then mash directly in the pot, Yukon is your better bet. But, remember to removed the potatoes and clean out the pot to remove the starch scum that will stick to the sides.For denser mashed potatoes, use a use a potato masher or fork to mash the PLAIN potatoes, while hot. An electric hand held mixer is great for making whipped potatoes. Use a medium speed.It is not recommended to use a food processor or immersion blender, as the starch will break down and mix with the potatoes and cause gummy potatoes.For those wanting to mash the steamed potatoes right in the Instant Pot cooking pot, make sure to first wash out the cooking pot. There is starch from the potatoes which will stick to the sides of the cooking pot. You don't want that starch mixing with the potatoes, as this too will cause a gummy mess.While I do prefer steaming the potatoes above a little water, some people do like to dump the potatoes right into the water or broth and cook, so that they can mash them right in the pot. Besides the issue of water logged potatoes (which isn't horrible if you only use a little water), there is the issue of gummy potatoes from mixing in the cooking pot directly after pressure cooking. The issue is the starch that clings to the side of the pot. As mentioned above, it is best to remove the potatoes, wash the pot and then place back into the pot, if you feel you must use your Instant Pot for mashing, as opposed to a mixing bowl.Amount of milk, butter, salt and pepper are personal preferences. Always start with less, as you can add more as you go. Once plated, people can add more butter and sale, so don't go overboard. :)The mashed potatoes should be a bit firmer than you like as adding the butter will loosen them up a bit, so go slow with the milk.For richer mashed potatoes, mix in 1/2 cup sour cream.