A short while ago, one of my daughters posted here about Pantry Staples. I would like to add my thoughts about pantry staples here because I think personally that these pantry staples should be everyone's pantry staples. The items I have listed here go a long way towards adding flavor, and should always be on hand.
Lemons - limes can be substituted for a slightly different twist.
Soy sauce - use low-sodium; soy sauce has so much flavor, and you really do not need the added sodium.
vegetable broth - again, low sodium works well. You don't need the sodium when you have the full flavor of the veggie broth which is so much better than just plain water.
vinegar - preferably apple cider vinegar, but you can try any variety. Go easy on balsamic, however. It has a lot of acidity.
capers - I don't know what these little buggers are but yum, they give a nice little kick when added with lemon juice. And just a small jar goes a long long way.
Roasted red peppers - chop them up and add them to rice, vegetables, or whatever and you've got a blast going on! They're great!
Well, that's all I can think of for now. But I think that's a good start to a well-stocked pantry of flavor.