Preparation

• In a medium bowl, whisk 3 Tbs. of the oil with the garlic, oregano, vinegar, 1/4 tsp. salt, and a few grinds pepper. Add the steaks and turn to coat. Cover and marinate in the refrigerator for up to 4 to 6 hours.

• Meanwhile, in a medium bowl, whisk the remaining 2-1/2 Tbs. oil, the parsley, capers, lemon juice, thyme, and chile flakes. Add the feta and stir gently to coat. Marinate at room temperature for up to 1 hour, or in the refrigerator for up to 6 hours.
• Prepare a medium-high (400°F to 475°F) gas or charcoal grill fire. Remove the steaks from the marinade and pat dry. Grill, turning every 2 minutes, until cooked to your liking, 6 to 8 minutes for medium (140°F). Transfer to a cutting board, cover loosely with foil, and let rest for 5 to 10 minutes. Thinly slice the steak against the grain, then season lightly with salt.
• Put the spinach, cucumbers, tomatoes, and olives in a large bowl. Drizzle all of the marinade from the feta over the salad, using a spatula to hold back the feta (it’s OK if a few pieces fall in). Season with salt and pepper, and toss to coat. Arrange on a serving platter or divide among four dinner plates. Scatter the steak and feta over the salad, and serve.