Given a paragraph about cooking, and a set of conversational question answers about the paragraph, answer a follow-up question from the paragraph. The paragraph has a prefix 'CONTEXT:'. Each conversation question has a prefix 'Q:' followed by answer prefix 'A:'. The final followup question has a prefix 'FOLLOWUP_Q:'.

[Q]: CONTEXT: In a cookbook that old, the sour cream referenced is probably a home-fermented variety, used as a preservation method in the days before widespread home refrigeration. You can still do this with the appropriate bacterial cultures, but most of us now buy our sour cream at the store instead. That product is similar, but made in much larger batches with a highly standardized, refined bacterial culture, producing a product with a predictable sourness and texture. Home-cultured versions are more variable, but they use similar processes on a much smaller scale.Whether you want to call this the "same" is partly a linguistic distinction that depends on how much you want to consider the differences in scale and equipment between pre-refrigeration and modern methods.In contrast, the addition of something sour to cream is really a substitute, used when you don't have a proper sour cream available. A cook back in the 1890s could use the same substitution then as we might today. But the production of sour cream (and all sorts of fermented milk products, such as yogurt and kefir) is much older than that, and there would have been some variety of "traditional" sour cream available, though not universally or year-round in the days before mechanized food distribution systems.  <sep>  Q: Is sour cream in olde recipes the same as sour cream today? A: the sour cream referenced is probably a home-fermented variety, used as a preservation method in the days before widespread home refrigeration  <sep> FOLLOWUP_Q: How would I make a home-fermented variety of sour cream?
[A]: You can still do this with the appropriate bacterial cultures, but most of us now buy our sour cream at the store instead


[Q]: CONTEXT: I think grilling is probably a bad plan for duck legs; the fat content is a real danger like you said, and duck legs are tough enough you probably want to confit them or braise them.If you absolutely have to grill them, I would suggest confiting them at 200 degrees for three or four hours first (you could use veggie oil in a pinch) and then resting them in the fridge for a day or so in oil. As for finishing them on the grill, rinse them off gently, re-season if needed, cook flesh side down on a medium heat portion of the grill for a while until mostly heated through, then flip them over on a high heat portion of the grill to crisp up the skin, watching out for flares.  <sep>  Q: Tips for grilling duck legs? A: I think grilling is probably a bad plan for duck legs  Q: What makes you say that? A: the fat content is a real danger like you said, and duck legs are tough enough you probably want to confit them or braise them  Q: How long should I confit or braise them? A: If you absolutely have to grill them, I would suggest confiting them at 200 degrees for three or four hours first  Q: At what temperature? A: 200 degrees  Q: Are there any other steps? A: then resting them in the fridge for a day or so in oil  <sep> FOLLOWUP_Q: What abouy the grilling process?
[A]: cook flesh side down on a medium heat portion of the grill for a while until mostly heated through, then flip them over on a high heat portion of the grill to crisp up the skin


[Q]: CONTEXT: Sous vide cooking is a function of temperature and the surface area to volume ratio of the food in question.If you have a high surface area to volume the cooking time will be shorter. Steaks would have a higher ratio than the roast so they would take less time than the roast. The amount of the time difference is difficult to predict exactly over such a long time scale, but a rough calculation of the ratio I spoke of would be a good starting point for a compensation factor.If you have the time and your water bath can accommodate, I'd suggest keeping the roast whole and finishing in a skillet. It's much more impressive than a steak.  <sep>  Q: Should I Sous vide chuck roast or chuck steaks? A: Steaks would have a higher ratio than the roast so they would take less time than the roast  <sep> FOLLOWUP_Q: Which would taste better?
[A]:
If you have the time and your water bath can accommodate, I'd suggest keeping the roast whole and finishing in a skillet. It's much more impressive than a steak