For anyone who grew up thinking of oatmeal as a gluey "instant" product from the microwave, encountering real oatmeal for the first time can be a real shock. The classic hot cereal, as enjoyed in the UK and elsewhere, is made with steel-cut or Scots-style ground oats, rather than the rolled flakes commonly seen on this side of the Atlantic. The two are different, but each of these styles of oatmeal makes for a much more appealing bowl of porridge.
Of Groats and Grinding
Oats are a superbly nutritious grain, but they're difficult for farmers and millers. They contain high levels of healthy oils, but also a troublesome enzyme that quickly turns those oils rancid. The cure for this unfortunate situation is to par-cook the oats with dry heat or steam, resulting in an oat "groat." While the oats are still soft from this process -- similar to the way wheat is processed into bulgur -- they can be rolled into the familiar flat flakes, or chopped into smaller, quicker-cooking pieces. Those small pieces are steel-cut or "Irish" oats, and if they in turn are rolled they produce quick oat flakes. The Scots, rather than chopping their oats, stone-grind them into meal much as Americans do with corn.
Steel-cut oats are relatively large, resembling the coarser grades of cracked wheat or bulgur wheat. They're usually prepared for breakfast by simmering one part oats in four parts of water for 20 to 30 minutes, until they reach the individual cook's desired texture. For those who dislike the thick and sticky texture of porridge made from rolled oats, steel-cut oats are a revelation. Because they're left relatively intact, more of the oats' starches and soluble fiber remain inside the grain, absorbing water and retaining a rice-like chewy texture. Enough of it cooks out to thicken the cereal, but there's a distinctive and pleasing difference in texture between the cooked granules of oat and the hearty porridge surrounding them.
Scottish oats are visibly different from steel-cut oats. When you open the package, you'll see a range of textures, from fine flour-like powder to relatively large fragments. Scottish oats are usually cooked a ratio of one part oats to three of water and, because of their finer grind, take only about 10 minutes to fully cook. Your finished porridge will have more of the distinctively sticky oat character, but retains enough larger pieces to provide an agreeable contrast of textures on your tongue.
Whether you cook Scottish or steel-cut oats, your porridge will be relatively thin while it's still at a simmering texture. If you remove it from the heat and let it rest for 5 to 10 minutes before serving, it will thicken noticeably.
For Baking Purposes
Rolled oats are a common baking ingredient, lending structure, nutrition and fiber to everything from cookies to breads. Scottish oats and steel-cut oats pack just as much fiber and nutrition, but they're more limited as a baking ingredient. Steel-cut oats are too large and cook too slowly to incorporate directly into recipes as you would with rolled oats. They're still a fine addition to breads, muffins and other healthy baked goods, but must be fully cooked first. To look at it another way, breads and muffins provide a good opportunity for using up leftover cooked oatmeal. The finer texture of Scottish oats means they can be added directly to doughs and batters. The finer, floury portion of the oats simply disappears into the finished goods, while the larger fragments provide a hint of chewy texture.