The best thing in Sitges ... Well, the best place to eat Japanese food that I've tried.
Tataki Roll (shrimp tempura inside, tuna "tataki" outside, and inside more goodies ... Best of the house)
What else to say? Ah well, yes: you have to go there. It's a must if you're in Sitges. But beware, Sitges in the summer, or a weekend that isn't in the middle of winter, you must call ahead, because that gets full. No wonder ;)