Gather 4 cups of cold water and 2 ½ cups of rolled oats.

Combine water and oats in a blender. Blend at medium speed for 35–40 seconds. Avoid overblending to keep the milk from becoming gummy.

Place a fine sieve or cheesecloth over a large bowl. Pour the blended mixture through the sieve, letting it drip naturally. Avoid pressing or squeezing the oats to prevent releasing extra starch.

For an even smoother texture, pour the strained liquid back into the cleaned blender, blend for another 15–20 seconds, and strain again.

Transfer the milk to a clean, airtight glass jar or container. Refrigerate for up to 5 days. Shake well before each use, as natural separation may occur.