The day before you want to make the dish, scatter half the salt, half the garlic and half of the herbs over the base of a small shallow dish
Lay the duck legs, skin-side up, on top, then scatter over the remaining salt, garlic and herbs
Cover the duck and refrigerate overnight
This can be done up to 2 days ahead
Pour the wine into a saucepan that will snugly fit the duck legs in a single layer
Brush the salt off the duck legs and place them, skin-side down, in the wine
Cover the pan with a lid and place over a medium heat
As soon as the wine starts to bubble, turn the heat down to the lowest setting and cook for 2 hours, checking occasionally that the liquid is just barely simmering
(If you own a heat diffuser, it would be good to use it here
) After 2 hours, the duck legs should be submerged in their own fat and the meat should feel incredibly tender when prodded
Leave to cool
The duck legs are now cooked and can be eaten immediately – or you can follow the next step if you like them crisp
If you are preparing ahead, pack the duck legs tightly into a plastic container or jar and pour over the fat, but not the liquid at the bottom of the pan
Cover and leave in the fridge for up to a month, or freeze for up to 3 months
The liquid you are left with makes a tasty gravy, which can be chilled or frozen until needed
To reheat and crisp up the duck legs, heat oven to 220C/fan 200C/gas 7
Remove the legs from the fat and place them, skin-side down, in an ovenproof frying pan
Roast for 30-40 mins, turning halfway through, until brown and crisp
Serve with the reheated gravy, a crisp salad and some crisp golden ptoatoes