Kale, Swiss Chard, Chicken, and Feta Salad

Ingredients

• 1/2 cup cider vinegar
• 2 teaspoons honey
• 1/2 teaspoon salt
• 1/2 teaspoon ground black pepper
• 1/2 teaspoon dried oregano (optional)
• 1/2 cup olive oil
• 1 bunch kale, torn into bite-sized pieces
• 1 bunch Swiss chard, torn into bite-sized pieces
• 1 pound grilled skinless, boneless chicken breast, sliced
• 1 (6 ounce) container crumbled feta cheese, or more to taste
• 1/3 cup raisins
• 1/3 cup chopped, toasted walnuts