Prep your vegetables: slice cucumber and thinly slice red onion.
Make the salad dressing: combine all ingredients in a jar and shake well until combined.
For the steak: Let steaks come to room temperature. Season each side well with salt and pepper. Cook over medium high heat, about 3-4 minutes each side, until internal temperature reads 140 degrees. Remove from heat, let rest 10 minutes. Slice for salad.
To assemble the salad: In a bowl, toss together greens, cucumber, red onion, sunflower seeds and dressing. Place on plates and top with hard boiled eggs and steak.