Blanch Brussel sprouts, heat water in a large stockpot. Once it starts to boil, add rinsed Brussel sprouts and let them boil for some time. The boiling time depends upon the size of the Brussel sprouts. You can blanch the larger Brussel sprouts for 5 minutes,

Remove Brussels sprouts immediately using a large slotted spoon. Drain and submerge into the ice bath to stop the cooking process.

Drain the Brussel sprouts and place them on a clean kitchen towel to get rid of excess water.

line the tray with parchment paper and place dried Brussel sprouts on it. Make sure there is some gap between vegetables. Place the tray in the freezer for about an hour. This process is called flash freezing and is crucial.

Lastly, take the tray out of the freezer. Place the frozen Brussel sprouts in a plastic zip-lock bag or container, seal it tightly and store it in the freezer. The Brussel sprouts are good to go for about 12 months.