To make a hearty and refreshing Steak Salad, follow these step-by-step instructions:

1. Prepare the Steak: Season the steak generously with salt and pepper. Let it sit at room temperature for about 10-15 minutes.
2. Heat the Pan: In a skillet, heat olive oil over medium-high heat until it’s hot but not smoking.
3. Cook the Steak: Add the steak to the pan and cook for 4-5 minutes on each side for medium-rare doneness (adjust the time based on your preferred level of doneness).
4. Rest the Steak: Once cooked, remove the steak from the skillet and let it rest for about 5-10 minutes. This helps retain its juices.
5. Prepare the Salad Base: While the steak is resting, in a large bowl, combine the mixed greens, cherry tomatoes, cucumber, and red onion.
6. Slice the Steak: After resting, slice the steak thinly against the grain.
7. Combine Salad Ingredients: Add the sliced steak to the salad bowl, then sprinkle with feta cheese, chopped nuts, and avocado if using.
8. Dress the Salad: Drizzle your choice of dressing over the salad. Toss gently to combine.
9. Serve: Divide the salad into serving bowls or plates. Enjoy your hearty and refreshing Steak Salad!