How sharp do knives need to be?

Since last week's post about Japanese knife sharpening techniques, I've been thinking about how sharp knives need to be, and tonight it all clicked. Sharp knives, aside from being safer and more efficient to use than dull knives, make food more attractive and contribute to the texture of the final product. But how sharp is sharp enough?

I remember with my old sharpening technique, a friend who sometimes worked as a professional cook was watching me cleanly slice a ripe tomato with my chef's knife, and said, "that's a sharp knife!" and it seemed so at the time.

When I started using a Japanese waterstone instead of the oilstone, I realized that I could dice a ripe tomato neatly, stacking two or three slices, cutting them first like french fries, and then dicing them crosswise. I could dice a tomato before, but not as quickly, cleanly, and effortlessly.

Tonight I was making leftovers. I had some tomato sauce from chicken cacciatore I'd made last week, and some grilled leg of lamb, so I thought I'd cut up the lamb and make a ragout to serve over pasta. I also had some very ripe tomatoes from the farmer's market to add to the pot. Tomatoes should be peeled before going into a sauce, or the peels become like little slips of paper, and the usual way to this is by blanching them briefly in boiling water, but for two or three tomatoes, it adds a lot of extra time to boil a pot of water. With my newly refined sharpening technique, I thought I'd see if I could peel them with a knife, and I did it with very little waste using the Henckels Four-Star 8" chef's knife that I've had for around 20 years, and it took less time to peel three tomatoes than it would have taken to boil two quarts of water. Then I could take these peeled ripe tomatoes, which are even softer than unpeeled ripe tomatoes, and dice them quickly, cleanly and effortlessly.

I used to think my knives were sharp enough, but now I'm doing things that with my old technique just wouldn't have crossed my mind.