How do you cut an onion to save half?

Cutting an onion efficiently can help reduce waste and save money. There are a few techniques that allow you to maximize the usable portion of an onion while minimizing waste.

Why Save Half an Onion?

Onions are a versatile vegetable used in many dishes. However, often recipes call for just half or a quarter of an onion. What do you do with the remaining unused portion?

Some options include:

  • Letting it go bad and throwing it away
  • Storing it in the refrigerator where it will slowly deteriorate
  • Freezing it for later use

None of these are ideal. Onions can be pricey, so throwing away half an onion can feel wasteful. Refrigerated leftover onion needs to be used quickly. And while you can freeze onion, thawed onion tends to be mushy which limits its uses.

Learning how to properly cut an onion to use just what you need and save the rest for later is a great way to reduce food waste and save money in the kitchen.

Cutting an Onion in Half

The easiest way to save half an onion is to cut it directly in half from root to stem. Here is the process:

  1. Trim off the root end of the onion
  2. Make one vertical slice down through the center of the onion, from the top to about 1/2 inch above the root end.
  3. Make horizontal slices across the onion, again stopping about 1/2 inch from the root end.
  4. Pull the onion halves apart.

This will leave you with two evenly sized onion halves. Use one half immediately for cooking.

To store the remaining half:

  • Place the unused half in a plastic bag or airtight container.
  • Squeeze out excess air and seal the container.
  • Store in the refrigerator for up to 1 week.

The intact root end and layers will help the unused onion half stay fresher longer. When ready to use, simply pull off layers or slices as needed.

Onion Wedges

Another option is cutting the onion into quarters or eighths. Here is how:

  1. Trim the ends of the onion
  2. Slice the onion in half from root to stem
  3. Lay each half flat side down and slice again from root to stem to quarter the onion
  4. For eighths, take each quarter and slice in half again root to stem

The advantage to onion wedges is you can take just what you need and leave the rest for later. They are easy to separate and store.

To store, place unused wedges in a plastic bag or airtight container. Squeeze out excess air and refrigerate. Use within 5-7 days.

Vertical Half

This method leaves you with one flat half for immediate use and a wedge-shaped half to store:

  1. Trim the ends of the onion
  2. Cut the onion completely in half through the root end
  3. Lay each half flat side down and make vertical slices from the top down to the root.
  4. The cuts should reach about three-quarters of the way down to the root

This will give you thin slices on one half, leaving the other half intact to use later. Place the unused wedge-shaped half in an airtight container and refrigerate.

Cutting Half an Onion for Caramelizing

Caramelized onions require lengthy cooking which softens and brings out the natural sweetness. Here are tips for prepping half an onion for caramelizing:

  • Peel the onion half, leaving the root end intact
  • Make vertical slices from top to bottom, again keeping the root end together
  • Cut the slices across the grain into roughly equal 1/4-inch pieces

This chopping method keeps the maximum surface area exposed for good browning and caramelization. Cook the onion low and slow, stirring occasionally, until deeply golden brown and softened.

Mincing Half an Onion

Finely minced onion is called for in many recipes like sauces, dressings, and salads. To mince half an onion:

  1. Trim ends and peel
  2. Cut the onion half from top to bottom into very thin slices
  3. Lay the slices in stacks and slice across the grain into tiny pieces
  4. Chop and gather the minced onion pieces

If the recipe calls for more than half an onion, simply repeat with the remaining portion. Store any extra minced onion in the refrigerator and use within 3-4 days.

Chopping Half an Onion

A rough or uneven chop is often called for in soups, stews, and chili. Here are some tips for chopping half an onion:

  • Trim and peel the onion half
  • Make a few vertical slices from stem to root
  • Lay the onion half flat and slice crosswise into pieces of varying sizes

The irregular sizes will add interesting texture. Use the chopped onion right away or refrigerate in an airtight container for 3-5 days.

Dicing Half an Onion

Uniform diced onion is the go-to choice for salsa, sauteing, and many other recipes. For evenly diced onion:

  1. Trim and peel the onion half
  2. Make close vertical slices from top to bottom
  3. Lay the onion half flat and slice crosswise into even strips
  4. Slice the strips across the grain into cubes

The diced pieces should be about 1/4 to 1/2 inch. Use immediately or refrigerate for up to one week.

Slicing Half a Red Onion

Red onions add a pop of color and mild flavor to salads, sandwiches, tacos and more. Here’s how to slice just half a red onion:

  1. Trim and peel the onion half
  2. Place it cut side down on a cutting board
  3. Make thin vertical slices across the grain from top to bottom

Aim for round 1/8-inch slices. Fan the slices out on a burger or sandwich, or separate into rings for salads and garnishes. Refrigerate unused slices in an airtight container for 2-3 days.

Julienning Half an Onion

Julienne means cutting into fine matchstick strips. Julienned onions are great for stir fries and fajitas. To julienne half an onion:

  1. Trim and peel
  2. Cut the onion half from top to bottom into very thin slices
  3. Stack 2-3 slices and cut lengthwise into sticks

Lay the sticks flat and slice again into thin 2-3 inch matchsticks. Use julienned onion immediately or store in the fridge for 2-3 days.

Chopping Half a Sweet Onion

Mild, sweet onions like Vidalia and Walla Walla are delicious chopped in fresh green salads, pasta salad, and salsa. To chop half a sweet onion:

  1. Peel and trim the onion half
  2. Make vertical cuts from top to bottom, leaving the root end intact
  3. Cut across the onion into pieces of desired size

Aim for a rustic chopped texture with pieces about 1/4 to 1/2 inch in size. Use right away or refrigerate in an airtight container. Will keep for about 1 week.

Onion Half Storage Times

How long leftover onion will last depends on the storage method. Here are general guidelines for onion half storage times:

Onion Half Storage Fridge Freezer
Intact Half Up to 1 week Not recommended
Wedges/Slices 5-7 days 2-3 months
Chopped 3-5 days Not recommended
Minced 3-4 days Not recommended

Onion wedges and slices freeze well for longer term storage. Simply place in a freezer bag or airtight container, removing excess air. Thaw overnight in the fridge before using.

Onion Half Substitutes

If you don’t have an onion half on hand, here are some possible substitution options:

  • Shallot – Use about 3-4 tablespoons chopped shallot in place of 1/2 onion.
  • Leeks – Substitute 1/4 cup chopped leeks for 1/2 onion.
  • Scallions – Replace 1/2 onion with 1/4 cup sliced scallions.
  • Asafetida – 1/8 teaspoon ground asafetida powder equals 1/2 onion.
  • Onion powder – Use 1/2 to 1 teaspoon onion powder for 1/2 fresh onion.

In cooked dishes, dehydrated onion flakes can also be reconstituted in water and used in place of fresh. Start with 2-3 tablespoons flakes for 1/2 onion.


With so many options for cutting, prepping, and storing, you can easily save and make full use of a whole onion, even if a recipe only calls for half. A little strategic slicing before use, and proper storage of the rest, can significantly reduce onion waste and save money in the kitchen. Next time a recipe calls for half an onion, try some of these methods to maximize use of the entire vegetable!

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