adapted from a Cooking Light recipe
2 teaspoons cumin seeds
Cut 1/4 inch off stem ends of peppers; discard stem ends. Using the tip of a paring knife, carefully remove and discard membranes and seeds, leaving peppers intact.
Using an outdoor grill or an indoor grill pan, place tomatillos and peppers on the grill over medium-high heat. Cook until charred on all sides- about 15 minutes. Put grilled tomatillos and peppers in a small bowl to catch juices.
Transfer the tomatillos and peppers to a blender, and puree until smooth. Add the onion, and pulse 5 times or until blended. Pour pepper mixture into a medium bowl. Stir in cumin, cilantro, lime juice, and salt.