Greek Salad with Marinated Chicken

Ingredients

• 1/2 cup red wine vinegar
• 1/4 cup fresh lemon juice
• 4 cloves garlic, minced
• 2 teaspoons Dijon mustard
• 2 teaspoons dried oregano
• 1 teaspoon kosher salt
• 1/2 teaspoon ground black pepper, or to taste
• 1 cup extra-virgin olive oil
• 1 pound boneless, skinless chicken tenders
• 1 tablespoon olive oil
• 1 (6-ounce) bag sweet butter leaf lettuce mix (about 5 cups)
• 1/2 of a red onion, thinly sliced
• 12 red cherry tomatoes, halved
• 1 small cucumber, sliced
• 1/2 cup mild sliced pepperoncini
• 1/2 cup pitted kalamata olives, halved
• 1/2 cup feta cheese chunks
• 1/2 cup roasted chickpeas (see recipe)