Gather and prep all ingredients. If preferred, wash and trim green beans. Season steak(s) with salt and pepper.
Add butter to a pan over medium-high heat. Once hot, add in the steak and fry until browned on both sides. A few minutes per side, depending on the thickness of the steak. Once finished, set aside and wrap in foil to rest.
In the same pan, add green beans and season with salt and pepper.
Cook green beans until crisp, but tender. Add in the walnuts and lemon zest and stir to combine. Cook for an additional 30-60 seconds or until fragrant.
Plate the green beans and steak. Pour any pan drippings over the top and enjoy!
Notes
This makes a total of 1 serving of Sirloin Steak with Lemon Walnut Green Beans. The serving comes out to be 631 calories, 44.1g fats, 4.9g net carbs, and 49.7g protein.