9 dried ancho chiles (scant 4 ounces), stemmed, seeded, torn into pieces
6 dried guajillo chiles (1 ounce), stemmed, seeded, torn into pieces
5 cups very hot water
4 garlic cloves, peeled
1/2 teaspoon dried Mexican oregano
2 teaspoons fine sea salt
Heat heavy large skillet over medium-high heat 2 minutes. Add all chile pieces; cook just until chiles blister, pressing with metal spatula and turning occasionally, about 30 seconds. Transfer chiles to bowl; add 5 cups very hot water. Soak chiles until very tender, pushing occasionally to submerge, about 30 minutes.
Working 3 batches, puree chiles with soaking liquid and all remaining ingredients in blender until smooth. Season sauce with more salt, if desired. (Can be made 1 day ahead. Cover and refrigerate.)
