There are fancier and better known Italian restaurants in San Francisco, but none reminds me of my Roman roots more than Ristorante Ideale (ee-day-AH-lay). This is true comfort food for me in every sense of the word. When I eat the pastas, I am immediately taken back to my aunt's kitchen in Rome where I spend most of my time sitting by her stove whenever I visit.
Though there are restaurants in San Francisco that get more attention for their "authentically Italian" pizzas, if the chef/owner of the restaurant isn't Italian that's a big strike to start. The pizzas at Ideale are incomparable. The thin cracker crust is just what you would find on the streets of Positano or Rome. Pizza has to be in your blood to have it taste like Italy (in my opinion), and this is the only pizza I will happily eat.
We had a lovely dinner at Ideale last night (until Wallie's meltdown caused us to have to leave), and the best surprise of all was seeing the owner's wife and her two girls. We used to be part of the same playgroup before we all moved away from San Francisco, but even though I know her, I would rave about the restaurant just the same. It truly is one of San Francisco's gems. You should go.