For hot oatmeal: In a large, microwaveable mug or bowl, mix the oats, ground flaxseed, hemp seeds, chia seeds, cinnamon, and salt. Helpful hint: The container needs to be at least twice the volume of the dry oat mixture to allow room for expansion. Especially when cooking in the microwave with milk, more room is helpful to prevent boiling over.
Prep-ahead tips: For oatmeal packets at the ready, you may mix as many servings of the dry ingredients as desired. Simply add to individual zip-top bags, reusable plastic containers, or glass jars with lids. The dry packets will keep in a cool, dry place for several months. If you are using a granulated sweetener or dried fruit, you may add them to the dry mix or use as a topping. For their natural sweetness, I often add a tablespoon of raisins to the packets.
To prepare oatmeal in the microwave: Add ¾ cup milk or water and stir to combine. Microwave on high for one minute, stir, then microwave in 30 second intervals until thickened. Add the additional liquid, a splash at a time, to reach your desired consistency. (Total time is 90 seconds in my microwave for quick oats and 2 minutes for old fashioned oats, but microwaves do vary.) Let the cooked oatmeal sit at room temperature for about 2 minutes; it will plump and thicken further. Top with or stir in extra ingredients of choice and enjoy.
To prepare oatmeal with boiling water: Add ¾ cup boiling water and stir. Cover and let stand for 2-4 minutes to soften and thicken; stir, adding a little more water or milk to loosen, if needed.
To prepare cold overnight oats: I prefer milk over water and the thicker cut of old fashioned oats for this preparation, although quick oats will work. Add ¾ milk (or start with ⅔ cup if you prefer a thicker consistency) to the dry ingredients, stir to combine, and then refrigerate for 8 hours or up to 3-4 days. Add another splash or two of milk upon serving to loosen the oats, if desired, and stir in any add-ins. Serving suggestions: With this method, I often add a drizzle of maple syrup, ½ cup of blueberries and/or chopped banana, and 1 tablespoon of toasted, slivered almonds. A mix of vanilla yogurt and milk is appealing too.