Ever cut into an avocado for lunch prep, then opened the fridge the next day to find a sad brown smear where the green used to be? I stopped wasting avocados once I learned the water trick, and it changed my meal prep.

The water trick for halves

Leave the pit in the half you are not using. Put the avocado half face down in a small container and cover it with cold water, pit side down so the cut surface is submerged. Seal it and refrigerate. The water blocks oxygen, which is what causes browning. I have kept halves bright green for two full days this way. When you are ready, shake off the water and pat dry. The surface will look slightly softer, but it tastes completely normal.

For mashed avocado and guacamole

Smoosh the guacamole down so the surface is flat, then pour a thin layer of water or lime juice on top before sealing. I use water because lime changes the flavor after a day. Press plastic wrap directly onto the surface instead of just over the rim if you skip the liquid. The goal is zero air contact.

What about the onion trick?

Some people swear by storing avocado with a slice of onion. The onion releases sulfur compounds that slow browning, and it does work, but your avocado can pick up onion flavor. Fine for tacos, weird for a morning smoothie bowl. I stick with water.

Quick rules that keep avocado green

• Keep the pit in until you serve it.
• Brush cut surfaces with oil or citrus if you are serving within a few hours.
• Store cut avocado away from the back of the fridge where it can freeze slightly.
• Do not freeze whole avocado. Mash it with a little lime first, then freeze.

The water trick costs nothing and takes ten seconds. I prep avocado for the week on Sundays now and it actually lasts.