Hello EfficientChef. Cooking a steak in a microwave and achieving a medium-rare finish without making it rubbery is exceptionally difficult, as microwaves heat water molecules via friction, leading to tough, grey meat rather than a proper sear.
If you need to avoid the oil from frying to hit your macros, I strongly recommend alternative fat-free or low-fat cooking methods instead of nuking it:
- Baking or Roasting: Place the sirloin on a wire rack over a baking sheet and cook it in a preheated oven at 400°F until your desired internal temperature is reached.
- Dry Pan-Searing: Use a heavy cast-iron skillet over high heat without any oil; a good quality pan won't stick if the meat is dry, and you can blot any excess moisture with a paper towel.
- Poaching or Steaming: Though unconventional for a steak, poaching in a flavored broth can cook it through without added fats, though you will sacrifice texture.
For a medium-rare steak, aim for an internal temperature of 130°F to 135°F using a digital meat thermometer. Microwaving will almost certainly ruin a yellow-sticker sirloin by overcooking the proteins instantly.