Serrano peppers can be eaten cooked, pickled, or raw either sliced, chopped, or pureed, and you can make a fine chile oil with them too. The stem is not eaten, and much of the heat is held in the seeds and inner flesh, which can be removed for a less-intense experience. The peel is thin and edible and is not typically removed.
Serrano chiles have a flavor similar to a jalapeño pepper, with a bright, fresh-tasting spice. They have a “delayed fuse,” meaning their heat takes a moment to fully kick in after it hits the palate. The level of heat for serranos often depends on their size (smaller often means hotter), color (unripe, green peppers tend to be milder), and the exposure they’ve had to the sun.