• 8 ounces (225 g) dried guajillo and/or New Mexico chiles (about 32 ), stemmed and snipped into pieces with scissors
• 12 chiles de árbol, stemmed
• 1 cup (60 g) sun-dried tomatoes

Shake out as many of the guajillo seeds as possible (but don’t lose your mind over it). Put the guajillo and árbol chiles and sun-dried tomatoes in the slow cooker and add 8 cups (2 L) water. Cover and cook on low for 6 to 8 hours.

Scoop the chiles and liquid (leave any sunken seeds behind) into a blender, working in batches if your blender is small, and let cool for a few minutes. Blend until very smooth. Set a fine-mesh sieve over a deep pot and pour in the chile puree, pushing the puree and liquid through with a spatula; discard the bits of skin and seeds in the sieve. Transfer the puree to freezer-safe containers in about 1½- or 3-cup (360- or 720-ml) portions and keep in the freezer for up to 6 months.