To make the dressing, put the oil, vinegar, garlic and mustard in a salad bowl. Season with salt and pepper, to taste, and stir to mix. Add the chickpeas, kidney beans, onion, chillies and herbs and mix well. Cover and chill in the refrigerator for 2-4 hours to let the flavours infuse.
When ready to eat, add the chicken, tomatoes and cucumber to the salad. Season with salt and pepper, to taste, and toss well. Sprinkle with a few shavings of Parmesan and serve with warm