Lunch is almost a sacred word for Peruvians: in fact, it is still their main meal of the day, rather than dinner, despite the fact that the majorty of people cannot have lunch at home... because they are at work. Family gathering may have actually moved to dinner time, but lunch is the main meal and the opportunity to socialize with friends and co-workers. And sometime it is a good time for discussing businesses, too.
So, lunch is usually a nice experience in either top-class or budget places. We are suggesting some very nice restaurants, with memorable food, usually located near or within reasonably distance from touristic attractions.
Regarding seafood, which is very important in Lima since it is a coastal city, there are plenty of options. Some of them would be Embarcadero 41 Fusión, that blends Peruvian flavors with many international influences; Niqei and its distinctive Peruvian/Japanese fusion; or Cebicheria La Mar, that preserves the original creole Peruvian recipes and flavors.
Exploring another kind of Peruvian cuisines, there's Kamcha and its Andean flavors: T'anta and its homage to many Peruvian regional cuisines; or Pardos Chicken, for those in love with barbecued foods. Vegetarians have also some options, specially Alma Zen and El Vegetariano, both of them in Miraflores.