TheFork users who ate in Cap-d'Ail have said really good things about La Reginella, La table d'Elise and Il Fornaio. Maybe you should give them a try!
Some of the more popular Trattoria restaurants that offer vegetarian options on their menu in Cap-d'Ail according to TheFork users include:
La Reginella, with a 8.6 rating
La table d'Elise, with a 8.5 rating
Il Fornaio, with a 9.7 rating