Pickled mushrooms

Mushrooms, 1-inch in diameter, stems trimmed, cleaned	3 pound
Vinegar, white	2 ½ cups
Water	1 ¾ cups
Pickling salt	3 tablespoons
Onion, red, halved lengthwise, cut into thin strips	½ small
Peppercorns, black	2 ½ teaspoons
Garlic	10 cloves

1. In a large pot, combine the vinegar, water, and salt; heat, stirring to dissolve the salt. 
2. Add the mushrooms; bring to a boil, then reduce to a simmer for 10 to 12 minutes. 
3. Pack the mushrooms in sterilized half-pint jars. 
4. To each jar, add several strips of onion, ½-teaspoon peppercorns, and 2 garlic cloves. 
5. Fill the jars with the hot brine, leaving ½-inch headspace. 
6. Remove air bubbles using a nonmetal spatula. 
7. Wipe rims of the jars and adjust the lids. 
8. Process for 20 minutes in a boiling water bath.