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It’s almost impossible to over-prep Thanksgiving. I say “almost” because my mom once cooked an entire Thanksgiving meal in advance, then reheated it on the big day. It was, shall we say, a new experience. One best kept in the past. Some things just don’t age well, especially when they’ve been cooked, but even the simple act of cutting a raw vegetable can kick off a process that affects the flavor and texture of the final dish. Some vegetables do fine when prepped a few days in advance, but others are best when chopped, sliced, and diced just before using. Here’s how to tell the difference.
Low-starch root vegetables
Let’s start with the good news: There are a fair number of vegetables that you can peel and slice two or three days beforehand without any terrible side effects, like oxidization, significant loss of moisture, and slimy decomposition. Low-starch root vegetables, like sweet potatoes, beets, carrots, radishes, and onions all have a two- or three-day window for peeling and cutting. For onions, wrap the cut ones in aluminum foil before packing it in a closed container to keep your fridge from becoming an oniony Pandora’s box.
How far in advance can you cut them: Two to three days in advance.
How to store them: Cut and placed in a lidded container in the fridge. Wrap onions in aluminum foil and then put them in a container to cut down on the aroma.
Some cruciferous veggies, fungi, and fruits
Cruciferous veggies happen to be some of the hardiest edible plants around. These are vegetables that have tough stalks and leathery leaves. You’re more likely to see them packaged in various stages of chopping at your grocery store. You can cut broccoli, cauliflower, Brussels sprouts, cabbage, and kale three or four days ahead of time with very little decomposition. Celery stalks and mushrooms can be cut three or four days ahead of time. Fruits that we commonly consider vegetables, like peppers, green beans, cucumbers, and squash, can be cut about two days beforehand without getting weird.
How far in advance can you cut them: Two to four days in advance.
How to store them: Cut and placed in a lidded container in the fridge.
Better to wait on delicate leaves
Think twice before cutting anything with a tender or delicate leaf. For some plants, cutting can severely damage the plant cells which will quickly manifest in bruising, and dark, mushy edges within hours (and sometimes minutes). Baby spinach, lettuces, and herbs are all best left to chop on game day. Particularly with herbs, you’ll get the most aromatic impact for finishing dishes if you mince them just before serving.
If you absolutely must chop any of these in advance, make sure you use a sharp knife. This goes for cutting in general, but a sharp knife with a fine cutting edge is going to cause less damage, slicing cleanly through plant cells, rather than crushing them like a dull knife will.
How far in advance can you cut them: A few hours before, or immediately before serving.
How to store them: Store delicate greens in a lidded container in the fridge with a paper towel tucked inside to absorb excess moisture.
How to keep starchy root vegetables fresh
Although non-starchy root vegetables will hold up days in advance, the starchy ones are more susceptible to oxidation and enzymic browning. You’ve probably seen this happen after slicing or biting into an apple, after five or ten minutes, the apple’s flesh begins to turn brown. This is a reaction the enzymes of the fruit or vegetable have once they’ve been exposed to oxygen. Starchy root vegetables like potatoes, parsnips, and turnips oxidize more readily than the vegetables mentioned above.
If you hate the idea of waiting until Thursday to peel five pounds of parsnips, you have a couple choices. The night before, peel or cut them and submerge them in water. The water will keep oxygen from interacting with the exposed vegetable flesh. The downside to this is that a vegetable like potatoes will lose starch to the soaking water, and if you leave them in the bowl for too long, they can become waterlogged and break apart. Another option is to toss any cut starchy vegetables in an acid like lemon juice. The acid contained in lemon juice will stop the enzymes from doing their browning business. Either way, chopping and treating starchy vegetables is best done no earlier than the night before cooking.
How far in advance can you cut them: The evening before cooking.
How to store them: Cut and submerged in a container of water in the fridge, or tossed in lemon juice and stored in a lidded container in the fridge.
I’ve named an assortment of popular vegetables above but it’s not an exhaustive list. When in doubt, think about if you’ve ever seen that fruit or vegetable sliced and packed in a container at the grocery store before. If you have, then you can chop, slice, or mince it in advance. If you haven’t, then it’s best to wait until you’re closer to cooking.