Preheat the grill to medium-high heat.

Season the steak with salt and pepper.

Grill the steak for about 4-5 minutes on each side for medium-rare, or until desired doneness.

Remove from grill and let rest for 5 minutes before slicing.

In a large salad bowl, combine mixed greens, cherry tomatoes, cucumber, red onion, and feta cheese.

In a small bowl, whisk together olive oil, balsamic vinegar, Dijon mustard, minced garlic, salt, and pepper to make the vinaigrette.

Slice the grilled steak against the grain and place on top of the salad.

Drizzle the vinaigrette over the salad and toss gently to combine.