how to prepare garlic and onion salt?

Answer 1

I'd do it by blending garlic (or onion) powder with regular salt. But I found these recipes that use fresh garlic:
http://www.recipezaar.com/56531
http://www.recipezaar.com/84831

Here's one for onion salt (warning-the site has a b'zillion popup ads):
http://www.recipecenter.com/Recipe.asp?code=65652

Answer 2

Hope this helps. I couldnt find on efor onion salt.

GARLIC SALT

3 days 5 min prep

3 cloves garlic
1/2 cup kosher salt

In a measuring cup quarter the garlic cloves.
Add the salt and cover loosley.
Allow the mixture to stand 3 days, stirring occasionally.
Leave the garlic in the salt until it is completely dried.
Remove garlic, transfer mixture to salt shakers.