This is a good recipe for times when you run out of soya milk. It's a fairly easy recipe to do and doesn't require a food processor (but like a lot of the things I do, it works best if you have a pestle and mortar for grinding the walnuts). It also has a nice taste. Almonds are also good in this recipe and if you do a wee search, you'll find a lot more almond milk recipes on the Internet than walnut ones. But almonds are really tough, so if you don't have an electrical grinder, you'll find using walnuts much easier. Cashews work too and they're also quite soft and easy to grind. Take your pick; they all taste good.
The raw milk will keep for a couple of days in the fridge, but the solids settle out fairly quickly and you'll need to give it a shake before using. Keeping the milk in a jar with a lid will facilitate this. You can use walnut and oat milk far all the things you'd use other milks for; it's great for making savoury white sauces. You can heat the milk too, for hot drinks. It will thicken a little because of the oat starch and it's nice sweetened with cocoa, or vanilla.
You'll also need a piece of cheesecloth for this recipe.
Grind the walnuts until they begin to form a very stiff paste. This will only take a few minutes. Put the ground nuts in a bowl with the oats (and a couple of teaspoons of sugar if you'd like to sweeten the milk; that can be nice if you use it for cereals) and cover with warm water. Give the mix a quick stir and leave to sit for an hour.
Lay a double thickness of cheesecloth in a sieve or strainer and sit it over a bowl or pot. Pour the mixture through and when most of the liquid has drained, gather up the edges of the cheesecloth and squeeze the rest of the liquid out.