The Rustlers Burgers are already cooked so all you need to do is heat the Rustlers burger up and if you want to you can eat the Rustlers burger cold.
Although the Rustlers Burger will taste much better if you heat it up first.
For me when I microwave a rustlers burger it's heated up within 30 seconds in the microwave at full power.
It can also depend on the microwave as some microwaves use less watts and require more power to heat the burger up.
But put the Rustlers burger in the microwave on high setting and heat it up for 30 seconds and then check it and if it's still not heated up enough microwave for another 10 to 15 seconds and it should be heated up and ready to eat.