I know that UK preserving standards would not pass muster in the US where everything seems to require some kind of heat treatment but here they are pickled in vinegar only and there doesn't seem to be a problem. Brine is used in the preparation but not in the pickling. Recipe

Yeah you can easily pickle anything in 100% vinegar and it is even more safe than the 1/2 and 1/2 I mentioned above. Problem most of the recipes call for very little vinegar.

This one calls for 2 cups water and only 2/3 cup vinegar.

This one calls for 1 cup water and only 3/4 cup vinegar.

This one is good as it is straight vinegar with no water.

But all call for fridge storage only.

This one from the UK adds bit of sugar, but it too calls for fridge storage even though it is straight vinegar, not canning.

Could you take one of the straight vinegar recipes and BWB it for 10 mins to get a vacuum? Very likely. But unkown what the heat effect on them would be.

Dave

A small issue with the Spruce recipe you give as 'this one is good' is the illustration. It shows brown dry nasturtium seeds. No good at all for pickles. You need fresh green, unripe seeds which you can only get if you grow your own. Just thought that needed mentioning in case anyone was misled into thinking we're talking about dry seeds here. My mum used to do them and afaik she just used the same spiced vinegar she made for pickled onions. We didn't own a fridge for some years so they were kept in the pantry.

Good point. My comment was only directed at the amount of vinegar called for in the recipe and I should have clarified that.

Dave

Oh, yes. I didn't mean there was an issue with the recipe, just that the picture could be misleading.

I make fridge pickled nasturtium capers... But not a canned one. For a couple reasons.

The primary one being that there aren't really any good safe canned recipes... and also, what might be fudged to pass for canning- I tried- yielded up a not satisfying caper result. The pods cook out too much or the vinegar brine increase to try to accommodate makes them way too much.

So, not Joy of pickling, but here's how I do it.

First off, picking your seeds right. Don't be tempted to pick tiny caper sized ones- you will only end up damaging the plant trying to pick them, and they aren't very good anyway. Seed clusters that want to break off and fall with the merest shake to the plant or touch should also not be used- ends up a bit too tough in the final product. You want ones that don't want to cling, and pinch off nice and easy with just a little bit of pressure into the palm of your hand. Your seeds should still be very green, firm. If you have any dried up bits like petals or leaves to pull off, now is the time while you are picking as much as you can.

Take a large jar with you for picking. I tend to use a quart jar and pick about a half pint to a pint of seeds at a time. After picking the jar is your wash tub. Once I have a jar of seeds, I take them in for processing.

First, I fill the jar up about halfway with clean water- good inch or two above the seed line. Swirl it around a good bit, but don't shake it. If you still had bits stuck to your seeds, it should float to the top, and get skimmed off. Rinse and drain your seeds. Don't air dry them, the water left on the seeds is important for the next part.

Mix your seeds with about 2T of kosher salt in a bowl and let them sit covered for about 30 minutes to start weeping. While your seeds are weeping, time to make the brine..

Use 2T canning salt per 1 c water. Sounds like a lot. Bring the water up to high heat to dissolve the salt and just boil the water, you will be hot packing this.

The next part is a bit of fermenting, I use brewers locks for this rather than taking chances with some other methods. Sanitized jar, lid, cork, and fermenting lock, every time. I use a jar oversized for this- if I pick a half pint, I use a 12 oz jar, if I pick a pint, I use a pint and a half jar.
Pack your jar with seeds, then ladle in the hot salt brine- you should cover the seeds by a goodly half inch or more with liquid. Nasts can float and settle. Put in a cap to keep the seeds submerged. Then cap with your ferment lock and let sit on the counter for 48-72 hours depending on the temps. You don't really want to ferment these, but rather give them a goodly saltwater soak.

After soaking, rinse off the nasts and start with a fresh jar- this one is your actual fridge jar.

Boil up a fresh batch of brine- I use 1 C white vinegar, 1 C water, 1 T salt ratio. No additions, or spices, just straight brine. Once it comes up to a boil, hot pack the seeds, cap with a lid and ring, and let sit on the counter for a half hour or so to let it cool off enough to put into the fridge. It might do it's own vacuum seal during this- do not trust that, it's not canned, not safe shelf stable.

It needs to cure for at least 4 weeks, and should be eaten up within 6 months at uttermost hopeful best. Around here we haven't successfully hit the 6 month mark yet- we tend to run out of them about the 4 month mark, and have to buy real capers again to cover the few months till nast capers are flush again.

And since I'm a big nast fan... something to do with those overripe seeds that aren't really suitable for pickling for capers since they are too tough, but just lux drop off while picking and you can't resist using them? Grind them up pesto style and freeze them off in cubes. Overripe for pickling caper nasts are great peppery green grind to pesto. Their leaves and their flowers also make great freezer pesto. Every year I grind up an icecube tray or few of the leaves and separate the flowers for excellent tasty through the year.

There's also using the dried seeds as a black pepper substitute. Unless you set yourself up early to do this.. don't do this. Happenstance dried seeds used as pepper is kind of yucky. Ok, very yucky.