Some Restaurants:

Pizzeria Paolo - in Chio. Take away Pizza 

La Pizzeria de Guia - in Guia de Isora - Italian 

El Rincon de la Barriga - in Alcala - Tapas, Fish

Sauco - in Alcala - Fish and Italien inspired - nice location at the sea front

Bar Arepera kilometro 101 - in Santiago del Teide - South American, not very cozy but great Arepas

Chintuma - in Playa San Juan - Mexican cuisine - everything fresh.

Sesto Senso - in Playa San Juan opposite of the beach - Italien inspired. A bit more expensive but great quality. 

100% Pan - in Playa San Juan - Award winning bakery. They serve good breakfast and if you go there on a Wednesday morning, you will find the farmers marking right in front of the bakery.  

Capuccino Maria - in Puerto Santiago - Tapas und coffee at the sea front