Wash and chop up your plums. I like to leave big chunks, because the fruit cooks down quite a bit and your pieces will shrink. Toss them in a big pot – ideally big enough that you only fill it halfway (sometimes jam sputters; you don’t want to get burned). Throw in some sugar. The nice thing about freezer jam is that you don’t have to worry about pH so you can make a slightly less-sweet jam if you prefer, which I do. Typically I start with enough sugar to coat all the fruit; here I used probably ended up with two or three cups of sugar for eight cups of fruit. (That may sound like a lot, but most recipes call for more sugar than fruit.)
Add some acid, to brighten the fruit up and for food safety reasons. Even though we aren’t using a waterbath canning method, we still want to discourage any little bugs that might be hanging around. I used the juice of two lemons, and then zested them, too, because why not? Also throw in a pinch of salt. If you have a lot of plums, make it a big pinch. Salt makes everything taste better; it adds vibrancy and dimension to sweet and savory things alike. Please don’t leave out the salt.
I think that basil complements plum flavors really well, so I also put in a bunch of basil leaves. The best way to do this is to bruise the leaves and put them into a metal tea ball, which is easy to remove at the end of cooking (the leaves detract from the texture of the finished jam). Since I don’t have a tea ball at the moment, I carefully cleaned a few stalks of basil (washing them then removing flowers and loose leaves), put them into the mix intact, and fished them out at the end.
Bring the whole mess to a simmer. You’ll probably want to start on medium heat to get the simmer going, but once you’ve got it going it’s best to reduce the heat to low so that you don’t accidentally scorch the bottom or have it boil over.
Let it cook. Stir it every now & then, making sure to get all the way down to the bottom so it doesn’t stick or scorch. If you have it on low heat, every ten to fifteen minutes should be fine. Cook it down until it has a jammy/saucy consistency: this will take a while. I cooked mine for about ninety minutes on low. Keep in mind that the jam will thicken a little bit as it cools, hence you want it to stay a little saucy in the pan. If you undershoot and it’s still runny when it cools, don’t worry. Just put it back over the heat and cook it down a little more. There are plenty of websites that can offer instructions on how to tell if it’s “done;” to be honest, I find that cooking by feel and taste works just as well.
Speaking of taste, taste as you go (just don’t forget to blow on the spoon a lot before you taste it – sugar gets hot hot hot). If your jam isn’t as sweet as you want it, add more sugar. If the basil flavor is strong enough for you but the jam is still thin, take the basil out early (I left mine in the whole time because I like really strong flavors). If it needs a little something but you can’t tell what, try adding a splash more lemon juice. If that doesn’t improve it, try a little more salt. One of them ought to do the trick. Tinker with it until it’s right. The best part of making your own jam is getting to make it taste exactly the way you want it to.
Let it cool and store it in the fridge or the freezer.
- This method will work with most fruits, and most fresh herbs. Think strawberry and sage, peach and thyme, mango and mint…
- If you plan to water-can your jam, please use a tested recipe! Water canning requires the jam to achieve a specific pH, and I haven’t bothered with that here.