Wisk together the buttermilk, roasted garlic (preferable still warm), vinegar and salt in a small bowl.
Add the cayenne peper or smoked paprika 1/4 teaspoon at a time, tasting after each addition.
Refrigerate in an airtight container until ready to use; shake before using.
Note: To roast garlic, Slice the top off 1 head of garlic so that the tops of the cloves inside are exposed. Lightly drizzle with olive oil and wrap tightly in aluminum foil. Bake in a preheated 425-degree oven for about 45 minutes or until garlic has softened and browned, set aside until cool enough to handle, then squeeze the softened garlic cloves out of there skins and discard their stem ends - dressing can be refrigerated up to two days in an airtight container.