Sara is a sleek, modern bistro with dishes made from fresh, local foods. It would fit in better on the West Coast of the USA than it does in the narrow, cobblestone streets of Cuzco, which is probably why most of the guests appeared to be European or American. If nothing else, this restaurant has some of the most innovative tableware that I have ever seen.
As for the food, vegetarians will find several items on the menu (which changes seasonally). When I was at Sara, there was one vegan-izable dish available in each course. The bread comes with a dollop of balsamic vinegar and olive oil. In the appetizer section of the menu, there was a mushroom ceviche. For the entree, there was a pasta dish, prepared with olive oil, capers, two types of olives, and roasted garlic (note: you have to specify "no anchovies," even though they aren't mentioned anywhere in the menu description). For dessert, there was chicha morada sorbet. Chicha morada is a delicious purple corn juice that doesn't taste anything like corn. The flavor more closely resembles a green tea/fruit infusion with a slightly herbal taste.
Vegetarians visiting Cuzco will find Sara to be a welcome relief from the greasy faux meat dishes that are popular at other vegetarian-friendly establishments. The food is considerably more expensive than at most other restaurants in the area (approximately $20 US per person for appetizer, entree and dessert) but it's well worth the extra expense for a healthy, thoughtfully-prepared meal.