Cook the orzo in a large pot of salted boiling water for 8-10 minutes until al dente. Drain and rinse under cold water.

Preheat the grill to medium-high. Brush chicken breasts with olive oil, season with salt and pepper, and grill for 5-6 minutes on each side until cooked through.

Whisk together olive oil, red wine vinegar, lemon juice, Dijon mustard, honey, and garlic in a bowl to make the dressing.

In a large bowl, combine the cooked orzo, sliced chicken, avocado, tomatoes, red onion, feta, and herbs. Toss with the dressing.

Chill the salad in the refrigerator for 20-30 minutes before serving.