1. **Prepare the onion**: Start by peeling off the outer papery skin of the onion. Cut off the root end and the top of the onion.
2. **Cut the onion in half**: Place the onion on a cutting board and cut it in half from top to bottom, following the natural lines of the onion.
3. **Remove the outer layer**: Peel off the outer layer of each onion half if it appears tough or discolored.
4. **Slice the onion horizontally**: Place one half of the onion flat side down on the cutting board. Hold the onion firmly with your non-dominant hand and make horizontal slices across the onion, parallel to the cutting board. Keep your fingers curled under to protect them.
5. **Slice the onion vertically**: With the onion still flat side down, make vertical slices from top to bottom, cutting towards the root end but not all the way through. Leave the root end intact to hold the onion together while you chop.
6. **Dice the onion**: Turn the onion 90 degrees and make perpendicular cuts across the slices you just made. Keep your fingers curled under to avoid cutting them. The closer together your cuts, the finer the dice will be.
7. **Finish chopping**: Once you've made all the cuts, hold the root end of the onion and slice through the remaining piece to release the diced onion.
8. **Repeat with the other half**: Repeat the slicing and dicing process with the other half of the onion.
That's it! You've successfully chopped an onion. You can use the diced onion in your favorite recipes, such as soups, stews, salads, and stir-fries.