Gather all your ingredients including steel-cut oats, water, almond milk, chopped walnuts, ground flaxseeds, chia seeds, mashed banana, maple syrup, cinnamon, vanilla extract, and salt.
In your 6-quart Instant Pot, combine the steel-cut oats, water, almond milk, chopped walnuts, ground flaxseeds, chia seeds, mashed banana, maple syrup, cinnamon, vanilla extract, and a pinch of salt. Stir well to ensure everything is evenly mixed.
Close the lid of the Instant Pot and ensure the valve is set to the sealing position. Select the “Manual” or “Pressure Cook” function and set the timer for 10 minutes on high pressure.
Once the cooking time is complete, allow the Instant Pot to naturally release pressure for about 10 minutes. After 10 minutes, carefully switch the valve to venting to release any remaining pressure.
Open the lid and give the oats a good stir. If you prefer a thinner consistency, feel free to add a splash more almond milk. Serve warm in bowls, garnished with chopped toasted walnuts, banana slices, and a sprinkle of cinnamon.