Sirloin Steak is usually tougher meat than most other steaks.
And also Sirloin Steak requires higher heat and quicker cooking times to make it less tough so you need to increase your heat and shorten your cooking time for the sirloin steak when you want it cooked to be less tough.
Cooking sirloin steak to well done but to where the sirloin is not tough takes around 11 to 15 minutes.
That is if you're cooking the sirloin steak in the oven.
Cooking the sirloin steak on the grill or skillet can take a bit longer.
You want to cook the sirloin steak in the oven at 350 F to 400 F degrees and preheat the oven before putting the sirloin steak in the oven.
Also make sure the sirloin steak is thawed out fully before cooking it so that the sirloin steak takes less time to cook and cooks more evenly.
You can also tenderize the sirloin steak before cooking it to make it less tough and make it easier to chew and digest.