For a simple but delicious lunch in Pedregalejo, Mafalda is a good option. Located around half-way down the seafront, Mafalda has all outdoor seating with views of the sea, perfect for lapping up the rays on a sunny day.
The restaurant is self-service, so you must go up to look at a menu before ordering.
For a typical local option, try one of the camperos (a kind of mix between a burger and a sandwich).
Vegetarian options are also available, and make sure to order fries separately if you are very hungry.