Start with the vinaigrette. Place all of the ingredients for the vinaigrette into a blender and blend until smooth. Taste, and season with salt and pepper if needed. Set aside.
About 20 minutes prior to grilling, remove the steaks from the fridge and let them come to room temperature. In the meantime, you can build your salads by evenly distributing the mixed greens, tomatoes, onions, olives, capers, feta, and toasted pine nuts into bowls. (I did not mark measurements for these things because this is a salad. When it comes to greens and toppings, use as much of or as little as you want.)
Preheat the grill to high.
Brush each side of steak with oil and season with salt and pepper. If marinated, skip this step.
Place the steaks on the grill and cook until they're golden brown and slightly charred, 3 to 4 minutes. Turn the steaks over and continue to grill 3 to 5 minutes for medium-rare. This of course depends on the cut and size of your steak, so look for an internal temperature of 135º F. If you want your steak done to medium, go for about 5 to 7 minutes, aiming for an internal temperature of 140º F, or 8 to 10 minutes for medium-well—150º F.
When done, transfer the steaks to a cutting board or plate. Tent them loosely with foil and let them rest for about 5 minutes before slicing them. Once sliced, place them over the salad and drizzle with the herb and garlic dressing.