Pour 1 ½ cups cold tap water into the the inner pot and add the trivet inside the inner pot.
Inside a 7-cup heat-safe stainless steel bowl or 7x4-inch cake pan, combine 1 cups steel-cut oats, 1 cup water, 2 cups dairy or non-dairy milk, 1 dash kosher salt, and ¼ cup ground flaxseed, if using. Please note that Pyrex is NO longer approved for use inside an instant pot.
Place the bowl on top of the trivet/rack and secure the lid on Instant Pot. Set Valve to "sealed" and set the cooking time for 8 minutes on high pressure using the manual or pressure cook function.
After 10 minutes, carefully release any remaining pressure and remove the lid.
Remove the bowl with the steel-cut oatmeal from the pressure cooker and serve with desired toppings.
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Notes
Steel-Cut Oats: Use regular, not quick-cooking steel-cut oats and select certified gluten-free if needed. Milk: Use dairy or non-dairy milk like coconut milk, almond milk, or soy milk. It is important to note if you are using a high-fat dairy (like coconut cream or whole milk), use no more than 1 cup of the full-fat dairy product and 2 cups of water. This will prevent the dairy from separating in the instant pot.Doubling the Recipe: This recipe can easily be doubled as long as it fits inside your heat-safe bowl. Using a 3-quart Instant Pot: Use a 6x4-inch cake pan and cut the recipe in half. Cooking Steel-Cut Oats Directly in Inner Pot: Combine 1 cup of oats with 3 cups of water (no milk or non-dairy milk) and cook on high pressure for 6 minutes with a 10-minute natural pressure release. Storage: Leftover steel-cut oatmeal can be stored in the fridge in an airtight container for up to 4 days. You can also freeze in individual portions for up to 3 months. Reheat individual servings in the microwave in 60-second intervals until warmed through, adding a splash of milk or water as needed.