preheat oven to 275 degrees. place chiles on a single layer on a baking sheet for 5 minutes or until chiles puff up. remove from oven and discard stems. split chiles and remove seeds. tear chiles into pieces and place into small bowl. pour boiling water over and let stand for 30 minutes. drain and reserve liquid. process chiles in food processor and form puree. add liquid and process to combine. this paste keeps several weeks covered in a jar.