In a saucepan, bring the broth to a boil. Stir in the orzo and cook until al dente. Drain and cool slightly.
Meanwhile, in a large serving bowl, season the vinegar with salt and pepper and mix until the salt dissolves; set aside. Whisk in the reserved olive oil. Add the orzo to the dressing and toss to mix.
Add the chickpeas, tomatoes, bell pepper, onion and basil to the orzo. Break up the tuna with a fork and add to the salad with the feta cheese.