Ingredients

2 tablespoons vegetable oil 

1 small onion, finely chopped (about 3/4 cup) 

3 garlic cloves, coarsely chopped 

2 1/4 pounds tomatillos, husked and washed 

1 fresh serrano chile, stemmed and seeded for less heat if desired 

2 tablespoons coarsely chopped fresh cilantro 

1/2 teaspoon coarse salt 

Preparation

Heat oil in a medium saucepan over medium heat. Add onion and garlic; cook, stirring occasionally, 1 minute. Stir in tomatillos, 1 cup water, and the chile. Bring to a boil. Reduce to a simmer. Cover, and cook, stirring occasionally, until tomatillos have softened, about 15 minutes. Drain, reserving 3/4 cup cooking liquid.Let cool slightly.

Working in batches, puree tomatillo mixture in a food processor with reserved cooking liquid. Add cilantro and salt; pulse to combine.