I just wanted to have a quick chat about marbling in beef, and steaks in particular.
In my Thai Seared Beef Salad with Mango & Peanuts recipe, I recommend that you seek out Flat Iron steak. Not just because it is cheaper than sirloin or rump, but in my opinion has a superior flavour and texture.
This is mainly due to the marbling in this cut of beef.
When fat forms between the muscle fibres in a piece of meat, it can often look like faint pale streaks running along the length of the dark muscle, and gives the meat a marbled look.
This is good to see, and it is this marbling of fat, known as intermuscular fat, that completely melts away and keeps the meat moist and juicy while cooking.
The grain in a piece of steak is simply the direction that the muscle fibres (marbling) are running in. To slice against the grain is to slice 90° or so to the direction of the muscle fibres.
If you slice with the grain, you will have long muscle fibres that will be chewy in the mouth. Slice against the grain and you are cutting short the muscle fibres, making them easier to chew and thus more tender.
I know it sounds a bit pedantic, but it is amazing the difference it makes to the enjoyment of a steak (or any meat) if you slice against the grain.