Preheat oven to 425°F. Remove husks from corn. Scrub corn gently with a stiff brush to remove silks; rinse corn and pat dry with paper towels. Remove the husks from the tomatillos. Wash tomatillos well in cold water. Cut the tomatillos in half and remove the cores. Coarsely chop tomatillos.
Arrange corn, tomatillos, and onion wedges in a single layer in a shallow roasting pan. Drizzle with olive oil. Roast 25 to 30 minutes or until vegetables are charred, turning corn and onion once. Let cool.
Carefully cut the corn kernels off the cobs. Chop the onions.
In a 4- to 5-qt. nonreactive heavy pot (tip, p. xx) combine tomatillos, corn, onion, chile pepper, vinegar, garlic, sugar, salt, and black pepper. Bring to boiling; reduce heat. Simmer, uncovered, 10 minutes. Remove from heat.
Ladle hot salsa into hot, sterilized half-pint canning jars, leaving a 1/2-inch headspace. Wipe jar rims; adjust lids and screw bands.
Process filled jars in a boiling-water canner 15 minutes (start timing when water returns to boiling). Remove jars from canner; cool on wire racks. If desired, stir snipped fresh cilantro into salsa before serving.
Prepare as above through step 4. Cool 30 minutes. Ladle salsa into freezer containers, leaving 1/2-inch headspace. Seal, label, and freeze up to 3 months.
(0 g saturated fat,
0 g polyunsaturated fat,
1 g monounsaturated fat),
0 mg cholesterol,
119 mg sodium,
7 g carbohydrates,
2 g fiber,
4 g sugar,
1 g protein.