In my experience, whether or not you peel a fruit or vegetable has more to do with how easy it is to digest than any level of toxins. If you're going into the realm of herbs, however, then you need to be more careful, as some are quite potent. But as long as we're sticking to fruits and veggies, here's my advice, and it's pretty simple:
Clearly things like melons, and corn don't have edible peels, simply because their outer layer is too difficult for us to masticate, and then digest... Things like citrus peels can be digested, but not when they're raw. They need to be pickled, cooked (think of marmalade) or turned into a zest. When it comes to soft, thin peels, like apples, pears and kiwi, it's more of a personal preference. Some don't like the feel of a furry kiwi slice going down, but I don't mind it, so I slice it right into my cereal.
In the realm of veggies... Yes, stems are great for you. If it's really difficult to chew it, it's not going to be broken down enough for your stomach to handle it, and extract anything useful from it. Ex: Broccoli stems - they'll benefit even from some light steaming, and they're GREAT for you. But raw? Rather difficult. The florets however are a classic raw snack. That's my general guideline. Same with artichokes. They need some kind of cooking in order to be digested. But carrots? Kale? Celery? Simple chewing pulls them apart enough to make the extraction of nutrients easy for the body.
Hope that helps!
Mindy
P.S. A great tip for raw kale - not everyone likes the consistency of raw kale because you have to chew it for soooo long. BUT, if you massage it with a bit of lemon juice, and a touch of olive oil until it softens, and the color brightens (5 minutes or less), it's easier to chew, very tasty, and you haven't cooked any of the nutrients out of it!
Personally, I would argue that 2 and 3 are actually the same, and they are your answer.
If you heat a pan of water you'll notice the bubbles forming before the water is actually boiling, hence the talk of between not bubbling and full on roiling.
Also, when you're making your soup, it isn't pure water, so the boiling temp will not be a perfect 100 degrees C in any case.
So, I would say, that simmering is when you keep it just under a full boil. Watch what you're cooking, there should be gentle movement, but not a full roiling pan of whatever it is you're cooking.
To get something simmering away, you need to bring up to a full boil, then reduce the heat until you're getting movement, but not full bubbling.
Best Answer
I don't think you physically can achieve the same results with a sous vide machine. Typically, those are designed to hold a water bath at a specific (relatively low) temperature. You can't hold water above its boiling point in an open container, because it's, well, boiling and will eventually evaporate. (You could do this in a sealed container, which is the principle behind the pressure cooker, but that's very different than sous vide.)
Here's the thing: simmering is gentle boiling, and by definition it occurs at (or just under) the boiling point of water. You cannot raise the temperature higher than that without adjusting other variables like pressure. Because solutes (like sugar) raise the boiling point of a solution, syrups will often come to a simmer well above the boiling point of plain water. So even if you placed your syrup in a bag, placed it in the water bath, and raised the water bath to a boil - the syrup in the bag wouldn't be boiling. You would have to add pressure or another solute (like salt) to the water bath to get the temperature high enough to also boil the syrup, which could very well damage your sous vide heating element.
The "half-candied" recipe you've linked is an interesting one, because it's really not traditionally candied. Instead what they're doing is infusing the orange with a high sugar content in order to preserve it in a similar way. That can only really be done in a low-pressure, vacuum-sealed environment, because it's using the lack of pressure to force the orange to absorb the syrup instead of boiling out the liquid to be replaced with syrup.
tl;dr: The temperature you need for the syrup to boil is higher than the temperature you can achieve in a sous vide bath. You will have to find another way to streamline the process.