Make the dressing first. Combine the oil, vinegar, garlic and mustard in a bowl and whisk them together. Season them with salt and freshly ground pepper according to taste and mix well. Add the chickpeas, kidney beans, onion, chillies and herbs to the dressing and stir to mix. Cover with cling film and refrigerate it for 2-3 hours so that the flavors blend well and you get the perfect taste that you want.
Just before serving, take out the salad. Add the chicken, tomatoes and cucumber to it and toss well to coat. Season with salt and pepper accordingly. Garnish with some Parmesan shavings. Serve with pita bread if you want to make it more filling.