Serrano peppers are slightly pointed and very hot. They are often used in guacamole and salsa and can also spice up a stir-fry.
In a small saucepan, combine canola oil, 2 serrano chiles, 2 sprigs oregano, and coriander seeds. Cook over medium heat, stirring, until fragrant, about 5 minutes.
Strain oil into a bottle; discard solids. Add another whole serrano chile and oregano sprig to the oil for garnish. The chile oil can be stored, refrigerated, for a few days; if the oil becomes cloudy, discard immediately.