5 medium Roma tomatoes, cored and halved (or an equivalent amount of other tomatoes)
10 dried Chiles de Arbol, stemmed and seeded
1 dried Pasilla chile, stemmed and seeded
2 tsp kosher salt
1 tsp sugar (less, if your tomatoes are particularly sweet)
1 1/2 cups water (less, if you're using juicy non-Roma tomatoes)
2 Tbsp hulled pumpkin seeds, toasted
2-3 Tbsp white vinegar
1/4 cup minced scallions
1/4 cup chopped cilantro
Preheat your broiler. Place the tomatoes in a greased baking dish, skin side up. Char under the broiler until the skins are slightly burned, and the tomatoes have started to give up their juice a bit (this can take just a few minutes).
Slide the tomatoes into a saucepan, along with the chiles, salt, sugar, and water. Bring to a boil, then reduce heat to simmer for 20 minutes, stirring occasionally.
Add the vinegar, cook for another minute, then turn off the heat. Add a scoop of this mixture to a blender along with the pumpkin seeds, and puree until almost totally smooth. Add the remainder, and puree until smooth (you want the pumpkin seeds totally blended into the body of the sauce, but specks of chile and such are fine). Stir in the cilantro and scallions, and taste to adjust seasoning. Allow to chill for several hours, for the vinegar to mellow and the flavors to meld. The salsa will thicken a bit the first day, and considerably the day after (if there's any left).