Thinking of ways to help a novice cook I ordered her a book about herbs and spices. It got me thinking that I depend on lots of things other than what's in the spice cabinet. Onions and garlic are a given. Then there's soy sauce, mustard, vinegar, wine, etc. I might also include tomato sauce and paste.
What pantry or refrigerator staples do you depend on for building those layers of flavors we all love?