Dull knives. It's the single biggest problem in home kitchens. The. Single. Biggest. Problem. It's the main reason cooking seems more difficult than it should be. And I'll say this again, too. Guys and girls, the best Valentine's Day gift you can give your lover/cook, get his/her knives professionally sharpened or buy a good sharpener. Again: Nothing says "I love you" like a really sharp knife. I get mine—I use Wusthof, btw—professionally sharpened at a wet-grind sharpening place, and OpenSky found this astonishingly effective and easy-to-use sharpening "stone," called the DMT Sharpening Stone. (It's not really a stone, but rather a patented diamond-dust coated perforated steel sheet on rubber; see video below.) If you have to saw on a lemon rind to get the ...