Pat the chicken breasts dry. If they are thick, place between two sheets of plastic wrap and gently pound to an even thickness (~1/2 inch). In a bowl, whisk together 2 tbsp olive oil, 1 tbsp lemon juice, 1 tsp dried oregano, 1 minced garlic clove, 3/4 tsp kosher salt and 1/2 tsp black pepper. Add the chicken and coat well. Marinate at room temperature for 15 minutes or in the refrigerator for up to 2 hours.

Grill

Preheat a grill or grill pan to medium-high (about 400°F / 200°C). Brush the grill with a little oil. Grill the chicken 4-6 minutes per side, until an instant-read thermometer inserted in the thickest part registers 165°F (74°C). Remove from heat and let rest on a cutting board for 5 minutes, then slice thinly across the grain into strips.

Dressing

In a small bowl or jar combine 3 tbsp extra-virgin olive oil, 1.5 tbsp red wine vinegar, 1 tbsp lemon juice, 1/2 tsp Dijon mustard, 1/2 tsp dried oregano, 1/2 minced garlic clove, 1/2 tsp kosher salt and 1/4 tsp black pepper. Whisk or shake vigorously until emulsified. Taste and adjust seasoning. Set aside.

Salad Assembly

Prepare the vegetables: wash and dry the romaine and tear or chop into bite-sized pieces to measure about 6 cups. Halve the cherry tomatoes, slice the cucumber, thinly slice 1/2 cup red onion, halve the olives if not already, and slice the pepperoncini into rings.

Combine the salad base: In a large mixing bowl toss the romaine, cherry tomatoes, cucumber, red onion, olives and pepperoncini so they are evenly distributed.

Dress the salad: Pour about two-thirds of the dressing over the salad and toss gently to coat. Reserve the remaining dressing for guests to add more if desired.

Add chicken and cheese: Arrange the sliced grilled chicken over the dressed salad. Sprinkle 3/4 cup crumbled feta evenly over the top.

Garnish and finish: Sprinkle chopped parsley over the salad and finish with an extra grind of black pepper. Serve immediately with remaining dressing on the side.