According to Wikipedia, steel cut oats are:
Steel-cut oats are whole grain groats (the inner portion of the oat kernel) which have been cut into pieces. They are commonly used in Scotland and Ireland to make porridge, whereas rolled oats are used in England, other English-speaking countries, and Scandinavia. They are sometimes named after the grade of cut, e.g. pinhead oats; steel-cut oats from Ireland are sometimes called Irish oats. Steel-cut oats take longer to cook than instant or rolled oats due to their minimal processing, typically 15–30 minutes (though much less if pre-soaked). The flavor of the cooked oats is described as being nuttier than other types of oats, and they are also chewier.
All of which makes a lot of sense in the context of bread baking. Recently, I have been making a lot of whole wheat oat bread with rolled oats (or old fashioned oats) that I have soak in hot water before adding them to my dough. In this batch, I simply (and pretty lazily) added 100 grams of raw steel cut oats to a 500kg batch of whole wheat dough — no pre-soaking. One boule.
The results were interesting, though not 100% good. While the oats became a little softer and they added a little bit of a crunchy texture to the dough, they were just too hard and even a little bit gritty. You can see the oats (like little pellets) in the crumb of the loaf.
Here is the formula:
300 grams whole wheat
100 grams white whole wheat
100 grams general purpose
100 gram steel cut oats
30 gram olive oil
30 grams honey
25 grams mollasses
375 grams water (75% hydration)
Now I want to work out whether rolled oats are simply a better type of oat for whole wheat bread, or whether I can get a better result by soaking my steel cut oats (either overnight in tap water, or for a short period of time in boiling water). Time for some Internet research. Also, our good friend Peter Reinhart has written an entire book on baking with whole grains.