Sous-vide is the process of cooking things slowly at a precise temperature. One wonderful aspect of sous-vide is that foods can remain at that temperature for an hour or two while you wait for guests to arrive. Here is a great chart for time and temp: sous-vide-time-and-temperature-guide There are many great (and expensive) sous-vide machines on the market, but with a little practice, you can use the stove-top and a digital thermometer. Sous-vide roots can be a delight -- and most fresh roots can hang out in your refrigerator or pantry for weeks on end, making this almost a pantry dish!
Heat a large pot of water to 183 degrees (between 180 and 190 will do). Use a digital thermometer. Add the vegetables to a large zipper-top plastic bag (Careful with the bags that have the slider -- they tend not to close completely.) Add the salt, herbs, and olive oil, close the bag, removing as much air as possible. Manipulate the bag to coat the vegetables with oil. Submerge the veggies in the bag of water for roughly an hour. Tips: Set the digital thermometer to alarm at 190 degrees. If the water gets too hot, add cool water. A metal colander or pot can be used to weight the vegetables down. A binder clip can secure the top of the bag to the side of the pan. These roots can be eaten at any point, but emptying the entire contents of the bag into a skillet for a couple of minutes will help caramelize the outside, adding nice color to the delightfully softened roots.