Add oats and water to a large microwave-safe bowl. The bowl should be large enough to hold 8 cups of water, this is important! The oats will rapidly bubble, so if the bowl is not large enough it will flow over.

Tightly cover the bowl with plastic wrap and cook for 5 minutes on high power in the microwave.

Carefully uncover, stir, and cook for another 5 minutes or until tender and thickened.

In a medium saucepan bring water and salt to a boil.

Stir in the steel cut oats then reduce heat to medium-low.

Simmer uncovered, stirring every 5 minutes until the liquid is absorbed and oats are tender, about 25 to 30 minutes.

Add oats and salt to a medium bowl. Add 3 cups of hot water, stir, cover with foil, and allow to come to room temperature. Store the oats in the refrigerator overnight.

Add the oat mixture plus 1 cup water (or milk) to a large saucepan. Bring to a boil over medium-high heat, then reduce to a simmer over medium heat.

Stir and cook until the oats have thickened and still have a slight chew, about 5 to 7 minutes. Allow the oats to sit for about 5 minutes to absorb the rest of the water, then serve.

Add steel cut oats, water, milk, and salt to a 6-quart slow cooker. Stir to combine.

Cover and cook until the oats are soft and thickened, 3 to 4 hours on the high setting, or 7 to 8 hours on the low setting.

Turn off the slow cooker and allow oatmeal to sit for 10 minutes before serving to absorb all of the water. The oatmeal will thicken more as it cools down.