Take the chiles and cut off all the stems. Insert your bare fireproof macha fingers into each chile and gently dislodge the seeds. Or, improvise by taking an ordinary pair of closed scissors and carefully insert it in each chile as shown, and move it around. Shake out the seeds.
Over medium-high heat, toast the chiles on a lightly oiled comal [griddle] for 30 - 40 seconds on each side.
Place the chiles in a bowl and just cover them with boiling water.
Use a plate to press down and submerge the chiles. Let them soak for about 30 minutes.
Pour the chiles and the water and whirl them in a blender at high speed for 3 - 4 minutes.
Pour the chile mixture through a wire mesh strainer to remove the tiny bits of peel.
Red Chile Sauce should resemble and pour like just like spaghetti sauce. If the sauce is too thick, add more a little more water. Stir in the vinegar and salt to taste.