The easiest and by far the best way to cook a steak is by frying.
I prefer sirloin as it's a good mix of meat and fat. I usually choose about 6 to 8 oz per person.
You need to flatten and tenderise the steak a bit. I usually do this by thumping it a bit.
At this point season the steak with a bit of ground pepper. On no account add salt at this point as it sucks the juices out of the steak whilst frying.
You need to get your pan as hot as you dare and add no more than a teaspoon of oil.
Pop the steak in the pan and flatten it down with the back of a tablespoon.
For a 1" steak you need about 2 mins on each side for rare.
3 mins on each side for a medium.
and 4 mins on each side for a well done.
For a 1 1/2" steak add a minute for each side.
If you are adding a sauce, add it to the last minute of cooking.
Add the salt just before serving.