The best fries in Lima? Many restaurants take pride in their fries, especially in using “native” species, which is odd as they are all native (Peru is the origin of the potato). But, more to the point, restaurants are branching out instead of just using the usual yellow potato. The common Peruvian yellow potato is small and is not well suited to fries. This makes the efforts of Juicy Lucy and Bao more impressive. Another fashionable potato these days is the Huayro. Most places make good fries as fries are an integral part of two of the most popular dishes: lomo saltado and salchipapas.
Here are a few of the places that I recommend:
Osso: Yes, I think they might be the best. They are made from large yellow potatoes. The fries are big, hot, crunchy, hard, floury, yellow like out of crayon box, and screaming for mushroom sauce!
Quisso: The fries are slim like that place with the arches. The fries are fresh cut like in Five Guys. They use the Huayro potato. When the potato is fresh cut and dropped in the fryer, the liquid escapes like firecracker champagne bubbles all along the surface of the fries. Bonus is that these fries are then covered in cheese.
Bao?: small wedges of round Peruvian yellow potatoes fried hard to give them that oven roasted feel.
Cafe A Bistro: I’m told that this places does great fries. Possibly one of the most charming things about this cafe is that it it located next to a gas station.
Merito: They make yuca fries. The yuca/cassava is a root but if soaked ahead of time, it makes a great fry. The ones are Merito are enormous. 
***Updated February 19, 2020 to update Spizza’s new address**** So it’s Sunday night and you want to go out for dinner… Here are some of the places that I found. The restaurants are listed by how early you can eat dinner so that if you feel like eating linner/dinner at 5 pm, you can. Many of these restaurants are located in hotels or in Laromar Mall but I’ve noted that if that is the case. More power to you going out to eat on a school night!
Vegan food in Lima? Yes, apparently. I asked some vegans for their list of places to eat. This blog posting is cribbed off of their list (though, I think you can ask at any place and then can probably make it vegan for you.)
San Borja: