The water temperature doesn’t matter, but keep the pot about ⅓ of the way full. Have a steamer insert that also fits inside the pot, but wait to put it in for now. A steamer insert is basically a small metal basket that helps cook food by holding it above the water level. Make sure the water doesn’t reach the steamer basket or the crab legs.  If you don’t have a steamer insert, try using a metal colander. You may also be able to fit something like a wire cooling rack or foil inside the pot. The water level doesn’t have to be exact. The most important part is adding enough to last throughout the steaming process while also making sure the crab legs aren’t submerged. It isn’t necessary, but it will add some additional flavor to the crab legs. Slice up to 3 lemons in half lengthwise and drop them into the water. Then, peel the skin off a head of garlic. Split it in half before dropping the cloves into the water. You can use fewer lemons or garlic cloves if you wish. You could also use store-bought minced garlic or chop up the garlic bulbs if you prefer. Bring the water up to 212 °F (100 °C). Once it begins to bubble rapidly, it is ready for the crab legs. Since you aren’t using a lot of water, you won’t have to worry too much about it bubbling over. However, make sure you have enough water to last for at least 5 minutes. Do a final check on the water. It shouldn’t touch the steamer basket once you place it inside the pot. If the water level is too high, let the water cool, then pour some of it out into the sink. Fit as many crab legs as you can by laying them flat inside the basket. Overlapping them a little is fine as long as they are inside the pot. You can usually cook about 1.5 to 2 lb (0.68 to 0.91 kg) at once, but it depends on the size of pot and steamer basket you’re using. If you’re cooking a lot of crab legs, plan on dividing them into batches. This will ensure they all get an equal amount of time in the basket and plenty of steam. Stuffing too many in at once could cause them to cook unevenly. Check...

How would you rephrase that briefly using Vietnamese?
Đổ 3 cốc (700 ml) nước vào nồi lớn. Cho chanh cắt đôi và tỏi vào nước nếu bạn muốn nêm gia vị. Đun nước trên lửa lớn cho đến khi bọt sủi lăn tăn. Đặt xửng hấp và cua vào nồi. Đậy vung và đun trong 5 phút. Đun chảy bơ nếu bạn muốn làm sốt chấm cua.