Gravlax, also called gravad lax, is a traditional Nordic dish which uses salt and sugar to cure the salmon. Various herbs are used to give flavor to the salmon, typically white pepper and dill, and the salmon is eaten raw after the curing process is finished.  Note: because the salmon is never cooked, keeping preparation surfaces and tools especially clean throughout the process is highly recommended. Use high-quality salmon if possible, acquired from a trustworthy source. Using farm-raised salmon is recommended, due to a lower chance of health issues. Although the chance of parasites is not high to begin with, you can reduce the risk further by freezing the salmon first, then defrosting it. Use a pair of tweezers or a small knife and fork to remove the scales and bones of the fish. Leave the dark skin beneath the scales attached to the rest of the salmon. These cuts allow the spice mixture to soak into the salmon, giving it more flavor and better preservation. Chop up one bunch of dill, or about 8 tbsp (120 mL), and crush 1 tsp (5 mL) white peppercorns. Mix these into 3¼ oz (85 g) sugar and 4 oz (120 g) salt. Experienced gravlax chefs will vary the ratios of these ingredients to suit their tastes, but the large quantities of sugar and salt are important so the salmon is properly cured. Heap the spice mix onto the salmon fillets, turning the salmon to make sure it is exposed to the mixture on all sides. Place the salmon in a glass or stainless steel container, touching the salmon fillets together on the pink flesh side, rather than the dark skin side. Cover completely with plastic wrap, then press the fish down with any heavy object, such as a brick. During this time, the salt and sugar should melt into the salmon, adding a stronger flavor. If you are not comfortable preparing raw food, you may wish to move the fish directly to the refrigerator instead, reducing the risk of bacterial growth. Move the salmon to the refrigerator, keeping the weight on top of it. The longer you keep it there, the stronger the...

===
Write a summary of the previous text in Vietnamese:
Sử dụng công thức này để giữ hương vị cá sống. Sử dụng cá hồi tươi. Lóc xương và làm sạch vảy cá. Cắt nhiều vết nông trên bề mặt da. Kết hợp các nguyên liệu khô với nhau. Tẩm gia vị vào cá. Dùng vật nặng đè lên cá. Để cá ở nhiệt độ phòng trong 6 giờ. Làm lạnh cá từ 1 đến 3 ngày. Lấy cá ra khỏi tô. Thưởng thức cùng sốt mù tạc thì là.