Steaming on the stove is a gentle heat transfer method that eases your food into its cooked state, making it perfect for vegetables, or proteins that have a tendency to overcook if you’re not careful. If you have an Instant Pot, you might be tempted to treat the “Steam” function just as you would a steamer set up on your stove but that, my friend, would be folly.
As with any of the Instant Pot functions that require the lid to be on and the valve to be sealed, this function is performed under pressure, within the same ranges as the “Manual” function. If you simply press “Steam,” and press no other buttons, the Instant Pot will cook your food under high pressure (10.2-11.6 psi) for 10 minutes, heating the water you (hopefully) added to the insert and steaming the food in your steamer basket. If you press “Adjust” after “Steam” to change the setting to “More,” this program will last for 15 minutes, if you adjust it to “Less,” it will only last for three. If you want less pressure, simply press “Pressure,” and the Instant Pot will operate in a range of 5.8-7.2 psi. (Except in the case of the LUX series, which only features the high pressure mode.)
What does this all mean? For one, it means that the only difference between the Instant Pot’s “Manual” function and “Steam” function is that the latter has pre-programmed times, which you can also adjust with the “+” and “-” buttons. But in terms of food—which is what we really care about—know that steaming food in the Instant Pot is going to cook it a lot faster. This is fine for heartier vegetables—in fact, it’s extremely helpful—but for more delicate green guys, like broccoli or asparagus, it can be not so great.
For example, steaming broccoli on the stove to a wonderfully tender-crisp place takes about five minutes. To get broccoli that’s not complete mush in the Instant Pot, you have to set the time to zero (0) minutes, and even then I’ve found it comes out a little too cooked for my liking. Also, it ends up taking the Instant Pot longer to come to pressure than it does for me to bring a pot of water to boil and steam it on the stove, so I guess my point is that there is no reason to steam broccoli (or any delicate green veg) in your Instant Pot. (Also, the Instant Pot must remain closed while cooking, which means you cannot monitor the vegetables—a drawback when it comes to a food that is so easily overcooked.)
However, there are many vegetables that do benefit from the Instant Pot’s applied pressure, particularly tougher specimens like potatoes, carrots, and squash. (See this chart for cooking times, and stay away from those that have a suggested cooking time of less than three minutes.) Just don’t bother with the broccoli; overcooked broccoli is no fun at all.