On a separate note I have a sous vide questions that I haven't seen discussed yet:
How does one cook something like a duck breast sous vide? Does one have to render out the fat first, or will the sous vide cooking process provide sufficient temperatures to melt that fat away? Any suggestions?
There are as many ways to cook duck breast sous vide as there are to cook it in other ways.
The classic French approach to duck breast is to treat duck breast like the red meat that it is and cook it to medium rare.
I use a water bath at 131F/55C, I cook until the core reaches 130F/54.4C (see tables in this thread for the times). If you like you can then let it cook an additional there 20 min to 30 min for food safety.
Many French chefs serve duck breast even more rare than this - cooking only to 120F/49C. This is a matter of personal preference. A bunch of other chefs will worry about cooking it at that low temp and will cook it at 141F/61C instead, but I don't like like that hot.
You could, in principle, cook duck breast for a very long time (12 to 36 hours) at low tempertaure (I would use 131F/55C) to tenderize it similar to other kinds of red meat. Obviously this depends on the ducks as to whether the breast meat is tough or not. Given the duck that I use, I have not had to do this, but it is an interesting possibility. It would also be interesting for duck legs - traditionally one cooks them at higher temperature because the legs are tougher, but with long time cooking sous vide they might be fine this way. Something to try...
No fat will render at any of these temperatures, so you have two choices - serve the breast without the skin, or crisp the skin by searing under intense heat (broiler, blowtorch, griddle). Any method of cooking which renders the fat will ruin the meat under the skin. If you really want duck skin that is thin and crispy without a fat layer, you have to remove it from the meat and cook it separately.
Or you can overcook the duck breast, if you prefer (can you detect my point of view
), by cooking it at higher temperature. As an example, you can make duck breast confit by cooking it at 180F/82C - there is a whole thread on duck confit that discusses sous vide approaches. These approaches work for the breast too. Traditionally one uses legs because they were not useful for other dishes (too tough) so they were cooked as confit to make them tender and also preserve them.
Note that even cooked at confit temperatures for 8-12 hours, the skin will not render all of its fat, and will still need to be crisped or seared.