About Serrano pepper
The serrano pepper (Capsicum annuum) is a type of chili pepper that originated in the mountainous regions of the Mexican states of Puebla and Hidalgo. Unripe serranos are green, but the color at maturity varies. Common colors are green, red, brown, orange, or yellow. When pickled they are known as a sport pepper.
Serrano chiles are small and slender-up to 2 inches (5 cm) long and about ½ inch (12 mm) wide. These fresh green or red chiles are about as spicy as jalapenos, which are notably sharper and very hot. They are also sold in their ripened red form and pickled in brine. The name translates as "mountain" chili.
Their flavor is crisp, bright, and biting, notably hotter than the Jalapeno pepper they resemble, and they are typically eaten raw. Its Scoville rating is 10,000 to 25,000.