1. Combine the ingredients for the marinade in an airtight container or a Ziploc bag. Add the steak strips into the marinade, seal and allow to marinate in the refrigerator for 30 minutes to one hour. The longer it marinates, the more tender the meat is!

2. In the meantime, wash and drain spinach. Melt one tablespoon butter in a large skillet and cook spinach for 1 minute, turning occasionally, until just wilted. Set aside in a shallow plate and allow to drain from the cooking juices. Quickly rinse and pat the skillet dry.

3. Bring the steak to room temperature and melt 2 tablespoons butter in the same skillet over medium-high heat — reserve the juices of the marinade for later. Add the steak strips in one layer and season with salt and pepper. Sear steak strips for one minute without stirring, then quickly turn the steak strips to cook the other side. Do not overcook – remove the steak from the skillet and set aside to a plate. You can proceed by batches to not overcrowd the skillet.

4. Still in the same skillet, add the last tablespoon butter, garlic, lemon juice, red pepper flakes, beef broth, parsley, chives, and remaining marinade to the cooking juices. Bring to a simmer and allow to reduce for 1-2 minutes, stirring regularly.

5. Add the steak strips back to the pan and adjust seasoning if necessary. Push steak aside in the skillet and stir in cooked spinach (well drained, see note below). Garnish with lemon slices, more chopped chive, and parsley and serve immediately. Enjoy!

Notes:

• You can also cook your steak whole to the desired doneness, have it rest for a couple of minutes, then cut into strips afterward.
• Spinach tends to render a lot of water when cooking, make sure you cook it separately first, then drain thoroughly to remove excess water before adding back to the lemon garlic butter sauce.
• To make the dish more complete, you can serve with quinoa, rice, or pasta.