Drain & rinse the cashews & put into the bowl of your food processor with about half of the filtered water & process to a thick paste. Add remaining water & process for a couple of minutes. It will probably still be a bit grainy, but that's okay.
Pour the cashew mixture into a saucepan & heat very gently, stirring with a silicone spatula making sure it doesn't catch on the bottom. Add the coconut oil, sugar & salt. Keep stirring until the mixture has thickened & is gently bubbling. Allow to simmer for about 5-10 minutes, stirring constantly - don't let it catch!
Take off the heat & blend with a stick blender until smooth (you might have to do this in a few stages if your stick blender's engine gets hot!). Cooking the cashews softens them & thickens the mixture considerably, so it is easier to process to a smooth consistency without the need for a high power blender. It shouldn't take more than 3-5 minutes of blending to get a smooth result.
Transfer the cream to a container & allow to chill in the fridge for at least a few hours - must be thoroughly chilled before whipping.
When it's nice & cold, spoon the cream into a mixing bowl, add the icing sugar & vanilla, & combine with a hand mixer for a minute or so. Measure the margarine into a small bowl & beat it with the hand mixer until pale & fluffy, then add it to the cream, beating with the hand mixer for a minute or two. The cream will become thick & fluffy. If you find your cream is a little soft or curdled, add more margarine, a tablespoon at a time, until you achieve the correct consistency. May be refrigerate until needed without losing aeration; it will firm up quite a bit when chilled.
Firmer Whip: If you want an even firmer consistency, add an extra tablespoon of coconut oil when you're cooking the cashew mixture, as well as a teaspoon of agar powder blended into 2 tablespoons of water. Make sure you simmer the mixture long enough to dissolve the agar & activate it into a gel.
Variations:
Boozy Cream: Instead of adding vanilla extract, you could try adding a couple of tablespoons of liqueur to Firm Whipped Cream - yum!
Chocolate Cream: I have made Chocolate Whipped Cream by melting about 100g (3.5oz) of dark chocolate into the cashew cream mixture as it cooked. When you whip the margarine into the chilled cream, you can see little flecks contrasting against the chocolate. I microwaved the whipped cream in 5 second bursts, mixing after each interval, until the margarine had only just melted into the cream. You lose a little of the aeration, but still end up with a light mousse-like consistency. I recommend the Firm Whipped Cream recipe if making chocolate cream.
Berry Cream: You could also try adding pureed, sieved berries (raspberries or strawberries would be nice!) to Firm Whipped Cream just before whipping in the margarine.
Creme Patissiere: Fold a cup of Soft Whipped Cream into a cup of chilled vanilla custard to make Creme Patissiere. Maybe add coffee, liqueur or pureed fruit.
Raspberry Fool: Add extra icing sugar to the Soft Whipped Cream recipe so it's nice & sweet. Gently fold through some lightly crushed raspberries (or other soft fruit) but don't over-mix. Heap into parfait glasses & top with a fresh raspberry & sprig of mint. Wouldn't it be nice served with a hazelnut shortbread?
Lime & coriander Sour Cream: A savoury idea for the cream mixture from the Soft Whipped Cream recipe. Omit 2 tablespoons from the cup of filtered water, add 2 teaspoons of apple cider vinegar & an extra pinch of sea salt while cooking. Blend until smooth, as usual & allow to chill - but don't whip it! Instead, mix in the juice & rind of 1 small lime, 2 tablespoons of finely chopped coriander (cilantro), 2 finely chopped spring onions, 1/2 teaspoon of ground cumin & some ground black pepper. Serve with chili, enchiladas, tacos, etc.
Troubleshooting:
A few words about the margarine you use... Someone reported that their cream didn't whip properly, & I think the margarine is the culprit - it's the one factor I can't thoroughly test because I only have one vegan margarine available to me, Nuttelex, which I recommend to anyone in Australia to use for this recipe (Nuttelex is 70% fat, 6% from palm oil, with no hydrogenated oils). For people who don't have Nuttelex available, I recommend a full-fat margarine, not low-fat or whipped, as the high water content could cause curdling & the lack of fat means it won't whip properly. I am going to test the recipe again, using the vegan butter recipe from VeganBaking, & will update if that works (I hope it does, because a palm oil free option would be great!). Meanwhile, I would love some more feedback if anyone makes the cream successfully with something like Earth Balance Original (which is 78% fat) or Pure Sunflower (67% fat).
Still a little curdly? As I mentioned above, if your cream isn't emulsifying properly, the type of margarine you use could be the culprit. Adding another tablespoon or two of margarine can help if your cream splits or curdles, but another solution is to add a tiny pinch of guar gum - and I mean tiny, because adding too much will make your cream take on an unpleasantly heavy, gummy consistency rather than being light and fluffy. Guar gum is a natural emulsifier, and if used in moderation, can help you achieve the right consistency.
The whisk attachment... I have found that the balloon whisk attachments for my hand mixer don't whip the cream as successfully as the regular beater attachments.
Is your cream still a little grainy? Depending on the type of food processor or stick blender you use, you might find the cashews don't blend down as smoothly as you like, in which case, try this... Instead of soaking the whole cashews overnight, place the dry unsoaked nuts into your food processor & grind them to a fine powder (a little crumbly is okay). Then stir them into the quantity of filtered water stipulated in the recipe (straight into the saucepan is fine) & leave the mixture to sit for at least two hours (the longer than better, although put it in the fridge if you're leaving it overnight) & then carry on with the recipe as written. This is also good if you're in a rush or forgot to soak your cashews overnight!
http://www.magicjelly.com.au/blog/2012/07/vegan-whipped-cream