Get a skillet screamingly hot over a high heat. If you have a grill pan great but don’t stress.
Generously season your steak with salt & pepper. Lay in the pan, placing it away from you (that’s just a good habit to start.) If using a grill pan and you want to create the quadrillage diamond-shape grill marks, place your steak at a 45 degree angle (in relation to the grill pan’s 90 degree grill lines)
Cook on the first side for about a total of 5 minutes (remembering about half way to pick up and rotate the steak to the opposite 45 degree angle if going for the diamond affect)and then flip the steak and cook for an additional 5 or so minutes. Adjust cooking timing based on how well done you like the steak.
When it’s reached your desired wellness, remove the steak from the skillet and let it rest (this ensures that when you slice into it the juices don’t run out.) While it’s resting you can make a quick Dijon vinaigrette by using your sense of taste to improv the oil and vinegar measurements. It’s easier than you think: start with a spoonful of mustard, then add a splash of vinegar and whisk them together. Taste and adjust. Then, while whisking continuously, slowly pour the olive oil until it emulsifies. Season, taste, and adjust until you like it. Any leftovers can be stored in a jar for a couple days.
Dress some mixed greens and plate them. Thinly slice the steak & lay it across the greens, and tuck in!