Step 1

The chiles and seeds. Stem the chiles, then roll them between your thumb and fingers, pressing gently to loosen the seeds inside. Break in half, shake out as many seeds as possible, then place in a blender jar.

Step 2

Heat an ungreased skillet over medium-low. Measure in the sesame seeds and stir for several minutes as they brown and pop; scoop into the blender jar. Add the pumpkinseeds to the skillet. When the first one pops, stir constantly for several minutes, until all are golden and have popped up into a round shape.

Step 3

Blending the sauce. Pulverize the cumin, allspice and cloves in a mortar or spice grinder, then add to the blender jar along with the oregano, salt, garlic and vinegar. Blend for several minutes, until the mixture is orange-red and feels quite smooth when a drop is rubbed between your fingers.

Step 4

Straining and ripening the sauce. Strain through a medium-mesh sieve, working the solids back and forth and pressing them firmly; there will be a fair amount of chile seeds, skins, sesame hulls and other debris to discard, but be careful that there is no liquid trapped within them.

Step 5

Stir in ¾ cup water, then pour into a bottle, cover and let stand for 24 hours before serving.