It's sad we know, but try not to cry--that onion wants to be cut up and eaten. You're just helping it fulfill its destiny.
To complete this How-To you will need:
An onion
A long, sharp knife, like a santoku
And a clean cutting board
Tissues (optional)
And a paring knife (optional)
Step 1: Remove skin
Remove the outer layer of papery skin from the onion, cutting the stem off and then peeling the skin down toward the root end in strips.
Step 2: Grasp knife
Grasp the long knife in your dominant hand, holding the handle close to the blade with three fingers: your middle, ring, and pinkie. Curl your forefinger around one side of the blade while holding your thumb on the opposite side.
Step 3: Position blade
Grip one side of the onion with your non-knife-wielding hand to hold it steady. Position the blade so that it will slice the onion in half lengthwise, from the root end to stem end.
Step 4: Cut in half
Cut the onion in half.
Tip: To prevent yourself from tearing up when chopping onions, you can try an old folk remedy, like sucking an ice cube or balancing a lemon wedge on your upper lip, but the best method is to keep a box of tissues close by.
Step 5: Lay face down
Lay each onion half cut-side down on the cutting board.
Step 6: Slice horizontally
Turn one onion half so the stem end is on your knife-wielding side. Holding it down with the fingertips of your other hand, position your blade so it's about a ½ inch from, and parallel to, the cutting board, and slice horizontally through the onion from the stem end toward the root end.
Step 7: Parallel cuts
Slice the onion to within an inch of the root end, then withdraw your knife and reposition it to make another parallel cut above the first one. Again, stop short of cutting all the way through the onion.
Step 8: Reposition knife
Rotate the onion half so the stem end points toward you, and reposition your knife so the blade is perpendicular to the board, cutting vertically from end to end.
Step 9: More parallel cuts
Insert the tip of your knife about an inch from the root end of the onion and a ½ inch from the right side, and slice through to the stem end. Continue repositioning your knife to make parallel cuts to this, all the way to the other side of the onion.
Step 10: Cut vertically
Rotate the onion half back so the stem end is on the right, and position your blade so it's perpendicular to the board, cutting vertically from side to side.
Tip: Keep the point of the knife on the board and use a steady rocking motion to slice—not saw—the onion with the full length of the blade.
Step 11: Reposition & cut
Slice the onion about a ½ inch from the stem end, straight down to the board, and the cut onion will section itself into multiple pieces. Continue repositioning your knife to make parallel cuts to this, all the way to within an inch of the root end.
Step 12: Pile together
Discard the root end and pile the chopped onion together, then make the same horizontal and vertical cuts though the other half of the onion. You have now chopped an entire onion—and hopefully kept your tears at bay.
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