The advice to use a 'canning salt' no doubt comes from a country (such as the USA or Canada) that adds iodine to table and 'ordinary' cooking salts.
This is not required or standard, if it even happens at all, in the UK; so you don't need to worry about it.
You may also want to avoid 'anti-caking agents' though, which are typically added to fine table salts, ...
Generally 1 per of the total dish. Like if are cooking 100L of soup you would need 1kg of salt i.e. one whole packet.
So if you are cooking 1L of broth 2 teaspoon should be good, bcoz one teaspoon is 5ml.
Generally people are able to escape this without measuring and just by intuition "hmm this about feels right" because salt has a wide range. 0.75%...
I regularly use truffle salt in scrambled eggs, and it can be sublime! However, you have to be aware that the truffle aroma is rather volatile. The one we had lost its flavour completely after about 12 months. (And this also explains what Max points out - it should be added just before serving, or it will evaporate.)
There is also a huge range of prices/...
Cook them in dishes.
I use sun dried tomatoes in my go-to pasta sauce. While mine are usually in oil, I have used others in the past.
I suggest thinking of them in the same way as anchovies. On their own, they can be near inedible, but when cooked in a dish, they almost dissolve into pure flavor. The same can be done with your tomatoes: After a while, ...
Two potential solutions:
Buy a different brand, one that's not packed in salt. Most sun-dried tomatoes are air dried and have minimal salt content, even if they're not packed in oil.
Soak these the way you would salt cod: in the fridge, for a day or more, changing the water 2-3 times. This should remove the salt, but might also turn them to mush.
Salt is just ....salt....no matter how it is labeled (assuming it is not a spice mix, with other ingredients). It might be more finely or coarsely ground, but....it's all the same. Just use less...a sprinkle on each side. You can always add more when you serve if you desire.
Truffle salt is more a gimmick (of hostess gift) than something that is really useful.
Use it as a finishing salt.
I'd sprinkle it over rice or potato purée or roasted, or even boiled vegetables.
I would not use it for cooking; the truffle flavor will disapear.
The primary way that cheesemakers create salty cheeses is brining. And cheese brine needs to be quite salty to be effective, as cheese, even vegan cheese, isn't that absorbent. The standard is a "fully saturated brine", which is roughly 22% salt (ignore the egg in that recipe, it's just a float test).
You might think that, for a less salty cheese,...