Chopping an onion willy-nilly is probably ok - your dish will still taste like onion and the world will not end. BUT, if you chop your onion properly (like this), all the little pieces of onion will be (about) the same size, so they'll cook evenly and look great in the dish. It all boils down to cuts in three directions (once your onion is in half).
To start, cut one end off the onion (not the root side).
Place onion cut-side down, and slice down the middle of the root, cutting the onion in half. Remove the outside layer of the onion.
To dice the onion, you'll make cuts in three directions. First, lay your onion with the newest cut side down. Place the palm of your hand firmly on top to steady the onion, as you make 3-5 even cuts parallel to the table. Do not cut all the way to the root (the root will keep everything together until the end).
Your second cuts will be perpendicular to the table, with the tip of the knife toward the root end (just not reaching the root). Curl your fingers under so you don't accidentally chop one!
Your final cuts will be perpendicular to the cuts you just made. While you cut, all your diced onion will "fall off" - it's quite rewarding!
Here's a little chart that might help...
1. 2. 3.
Now...go make something delicious with your perfectly diced onions! Here are a few things I love to make:
Italian Chicken & Pasta
Our Favorite Chili
Spaghetti Sauce with lots of veggies
Honey Mustard & Apple Pork Tenderloin