If using dried chiles, dry-roast them in a small heavy skillet over medium-high heat until they soften, about 1 minutes. Turn out and coarsely chop; discard any tough stems. Transfer to a spice grinder or clean coffee grinder, or to a mortar, add 1 Tbsp of the salt, and rind or pound to a powder. Turn out into a bowl and set aside
Place the Szechuan peppercorns, and the black peppercorns, if using, in the skillet and dry-roast until just aromatic, 1 to 2 minutes. Transfer to the spice or coffee grinder or mortar, add the remaining 1 Tbsp salt (or 2 Tbsp if you aren't using dried chiles) and grind or pound to a powder. Add the powder to the ground chile-salt above. Let cool completely before storing in a clean glass jar
Notes
VARIATIONS: You can also use this mixture to flavor oil, for basting when you are grilling food. Stir about 1 Tbsp powder into 1/4 cup oil (suggested on olive oil, as well as in more traditional peanut oil or lard). Brush onto vegetables or meat just before you grill and/or as they are grilling