Step 1

Toast the guajillos in a 300°F (150°C) oven for 10 minutes, then cool. Break the stem off each chili and shake out the seeds. Discard the stems and seeds.

Step 2

Crush the chilies in a mortar and pestle so that they're coarsely crushed (you don't want a powder here) then mix with the crushed red pepper and reserve. Combine all ingredients except the dried chilies and black beans in a blender and puree until smooth, about 30 seconds.

Step 3

Pour the mixture into a small 2- to 3- cup (490–720 ml) capacity saucepan, add the guajillo or other chilis and crushed red pepper flakes, bring to a simmer, and cook on low heat until the liquid has evaporated, about 30-45 minutes.

Step 4

Watch the mixture carefully, as you don’t want to burn it.

Step 5

When in doubt, undercook it a bit as; you can always gently simmer it for a bit longer.

Step 6

When the mixture is starting to separate, stir in the beans, cook for a few minutes more, then set aside the pan to cool off the heat, and marvel at how great the kitchen smells.

Step 7

The sauce will last for a month in the fridge—longer if you make sure the solids are always covered by a layer of oil in the jar. Stir it before using.