One of the most versatile and necessary ingredients in a professional cook’s freezer is vegetable stock. It’s the perfect base for a quick sauce, a tasty soup, or flavorful additive to an everyday dish. Sure, it’s sold at the supermarket, but you can make your own vegetable stock with scraps you already have on hand for a fraction of the price.

You know all of those carrot shavings, potato peels, celery heads, and onion scraps? They’re usually things you throw right into the trash or compost. Why waste them?

Instead, when you’re prepping your meals, keep a big plastic bag next to the cutting board to capture all of those cleaned, tasty and useful items. When you’re done, throw them in the freezer until you have about a gallon sized bag.

Some great scraps to capture for vegetable stock:

• Onions

• Asparagus trimmings

• Celery heads

• Leeks

• Carrot peelings

• Potato peels (make sure they are clean!)

• Mushroom stems

• Parsnips

• Shallots

• Tomatoes

Some scraps to avoid for vegetable stock:

• Green beans

• Pumpkin

• Beets

• Cilantro

• Peppers

• Turnips

• Corn (both the cob and the kernels)

• Leafy vegetables (cabbage and lettuce)

• Rosemary

Once you’ve acquired all of the necessary scraps, it’s time to get your stock on. Grab a big old pot and add all of your frozen scraps. You’ll also want to add some sprigs of thyme, a bay leaf, and about 5-10 peppercorns to add a bit of extra flavor. Then, add cool water to the pot until the water just covers all of the scraps. Bring the pot to the stove and crank up the heat. Once the stock is brought to a boil, you’ll want to turn down the heat until you’ve got yourself a simmer. Keep the stock at a simmer until it has reduced by half.

Once the stock has reduced, prepare a sieve (a fine strainer) over another pot. Carefully pour the vegetable stock (scraps included) into the sieve to remove all of the solid scraps. Those scraps can now be composted or discarded (but know you’ve used them to their max!). What you’ll be left with is a deliciously flavorful liquid stock that can be frozen and used for up to three months.

Quick tip? Fill up an ice tray with vegetable stock. Once they’re frozen, throw them in a plastic bag and put them back in the freezer.

Whenever you’re in a pinch for a quick sauce, melt some butter in a pan and add some flour (while stirring) to create a roux. Add a cube of vegetable stock to the roux (again, while stirring). You can always add another cube if you’d like a thinner consistency, or fancy up the gravy with additional spices or pan drippings.