The more tender the meat you use, the smoother and better-tasting your puree will be. Whether you're pureeing beef, chicken, pork or lamb, you want to choose a tender cut that won't toughen up when cooked.  Often the cheapest cuts of beef are the toughest, so try choosing a cut like top sirloin. For chicken, you can buy the meat boneless or bone-in. If you buy it bone-in, you'll have to be careful to make sure no tiny bones get mixed in with the puree. Slow cooking methods help the meat retain flavor and moisture, making it much easier to puree. No matter what type of meat you use, consider cooking it slowly so you end up with the best possible texture. Here are some methods that work well:    Braising. Using a slow cooker.  Boiling The meat must be completely pre-cooked before you puree it. Check the temperature of the meat when it's done to make sure it has reached the correct internal temperature. Here are the correct temperatures for different types of meat:  Chicken: 165 °F (74 °C) Pork: 160 °F (71 °C) Beef: 145 °F (63 °C) Lamb: 145 °F (63 °C) After cooking, chill the meat in the refrigerator for at least 2 hours. The meat should be completely chilled in preparation for processing. Chilled meat will process into much finer pieces than meat that is still warm. Remove it from the refrigerator and chop the meat into chunks that will fit easily in your food processor.

TL;DR in Vietnamese:
Chọn phần thịt mềm. Nấu từ từ để làm chín thịt. Đảm bảo thịt đạt đến nhiệt độ phù hợp sau khi chế biến. Làm lạnh thịt. Cắt thịt thành miếng khoảng 2,5 cm.