Combine oats, water, and salt in the bowl of a 6-quart pressure cooker (Instant Pot). Secure lid, turn valve to seal if necessary.
2 cups steel cut oats, 5 ½ cups water, ¾ teaspoon kosher salt
Set to Pressure Cook (or manual, high pressure, depending on your model), for 5 minutes.
Once cook time has elapsed, let the pressure release naturally for 20 minutes. You do this by just leaving it alone. It has a timer that will count how much time has elapsed since it finished but you can also set a timer if you think you’ll forget to check.
When 20 minutes has passed, carefully turn the valve to vent any remaining pressure. Once the pressure has released, carefully remove the cover.
Stir the oatmeal, and serve with desired toppings. Oats will continue to thicken as they set. Makes 5 to 6 cups of oatmeal.
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Notes
Steel cut oats: Steel cut oats are not the same as old-fashioned or quick oats. The oats are not rolled into thin flakes but rather cut into small pieces, which take a little longer to cook. This recipe is designed for steel cut oats and won't work for other types of oats. You don't need to rinse or soak steel cut oats before cooking them.
Adjusting consistency: If you prefer thinner oatmeal, use 6 cups of water. I don't recommend using less water to make the oatmeal because you're like to get a burn notice on your Instant Pot. Remember, the oatmeal thickens as it cools.
Storage: Leftover Instant Pot oatmeal can be refrigerated for about a week. You can freeze oatmeal (I recommend freezing in individual portions) for up to 3 months. Thaw overnight in the fridge.
Reheating: Steel cut oats reheat very well on the stovetop or in the microwave. You might find they thicken a bit, but you can thin them down with water or a milk of your choice.