Here's What You Can Substitute For Onions
Onions are one of the most essential key components for building flavor in dishes. Recipes like soups and stews often call for a mirepoix, which is chopped onions, carrots, and celery. Roasts are often accompanied by carrots, onions, and potatoes. Onions are just a key ingredient in many recipes, and serve as a building block for developing more flavor and depth to food (via Taste of Home).
While onions typically have a long shelf life when stored properly, there's always a day when there just isn't one the pantry when you need it. Fortunately, there are plenty of alternatives to onions that can be swapped in to flavor whatever recipe you're cooking. Depending on what you have on hand, it's easy to make a few adjustments to a recipe that calls for onions.
If you have onion powder sitting among your spices, that's a great substitute. Frozen chopped onions can also be traded in. Other fresh options that can be used instead of onions include shallots, green onions, scallions, or even leeks (via Huffpost).
Measurements for onion substitutes
Onion powder is significantly stronger than a regular chopped onion, which means it takes a lot less onion powder to achieve the same flavor in a dish. For each medium onion that a recipe calls for, it only takes 1 1/2 to 2 teaspoons of onion powder to substitute. You'll also need less if you use frozen chopped onion or shallots in place of an onion. When a recipe calls for a medium onion, a cup of either frozen chopped onions and shallots can be added in the onion's place.
Finally, it will take more green onions, leeks, and scallions if you need to replace fresh onion when compared to any of the other substitutes. These are all like a milder version of your standby onion, so to achieve the same onion flavor, it takes about a cup and a quarter cup of chopped green onions, leeks, or scallions for each medium onion that a dish requires. If using scallions, stick to using only the white or light green part rather than the bright green ends for best results.