The pepper that originated in Mexico’s Puebla and Hidalgo regions is the serrano pepper.
Serranos are a cultivar of Capsicum annuum, the same species that includes jalapeños, poblanos, and many sweet peppers. Their name refers to the sierras, or mountainous areas, where they originated. The peppers are commonly harvested green, though mature fruit can turn red, brown, orange, or yellow.
Serranos are generally hotter than jalapeños, measuring about 10,000–25,000 Scoville heat units. They have a bright, biting flavor and are often used raw, where their crisp heat remains noticeable.
They are especially common in Mexican cooking, including salsa, pico de gallo, hot sauces, and some guacamole recipes. A frequent mix-up is confusing serranos with poblanos: poblanos are usually larger and milder, while serranos are smaller and considerably hotter.