"I left my home for about 4 months. When I returned many of my powdered seasonings had hardened. Onion powder, garlic powder. Is there a way to soften them or do I have to throw them out?"
First let me say that I have at least 6 cooking encyclopedias sitting on my bookshelf and I did a google search. Lots of places tell you how to soften brown sugar and regular sugar for that matter. I even shared a tip from Norene Gilletz and a couple from Waitrose...
...but nowhere do any of the experts tell you what to do with hardened powdered seasonings. So here's my two cents worth...and we all know what that buys these days.
If I have clumps in my mixed seasonings, I place it in a small tea strainer over a bowl. If it's a hard block...you might need to chip it out of the bottle with a small sharp knife.
That said, I must say that I do agree with all the experts...spices lose their potency and flavor over time.. everyone suggests marking the date on your spices when you buy them and throw them out after a year.
The other thing I suggest is to "toast" your spices before using them (even ground ones). Use a nonstick skillet/ fry pan..and over medium heat toast your spices, shaking the pan occasionally until you can sniff the fragrance....just takes a few minutes.
Of course the best way to get the most out of your spices is to buy them whole in small batches that you can keep in an airtight container and grind just what you need for any given recipe. The difference in flavor that this little effort makes will amaze you. I use my KitchenAid coffee grinder, because you can take it apart easily to clean. We wouldn't want coffee smelling like cumin or cumin flavoring our coffee for that matter.
Those were my attempts at helping out...now I turn to you for advise. Any tips on softening hard seasoning powders?
Just add them to the comments and I'll update the post.