TheFork users who ate in Aci Castello have said really good things about Faraglioni Restaurant, Mama Sea and I Conzari. Maybe you should give them a try!
Some of the more popular Lactose intolerance restaurants that offer vegetarian options on their menu in Aci Castello according to TheFork users include:
Terra Madre - Aci Castello, with a 8.6 rating
Masè Acicastello, with a 9.3 rating
Faraglioni Restaurant, with a 9.7 rating