Use your fingers to peel the thin, outer membrane off each liver. The membranes will come away easily. Try not to tear the liver as you remove the membranes. Liver is usually sold with the membranes already removed. Place 1 1/2 lb (680 g) of beef or chicken livers on a chopping board. Use a very sharp knife to slice the livers into strips. Be very careful when you use a knife to cut the liver thinly. Always make sure that you are using a sharp knife, as this is both safest and will make the best cuts. cm) slices. Place the onions on a chopping board and use a sharp knife to cut the ends off. Slice each onion in half and peel the skin off. Place the flat surface of each onion on the chopping board and carefully slice each half thinly. Pour ½ cup (64 g) of flour, 1 tsp (2.3 g) of freshly ground black pepper, and ½ tsp (2.5 g) of salt into a bowl. Use a fork to mix the ingredients thoroughly. Season the flour with more or less black pepper and salt depending on what you prefer. Place each slice of liver into the bowl with the flour, black pepper, and salt. Turn each slice over in the bowl to make sure that all of the sides are coated with the seasoned flour. Gently shake each slice of liver as you take it out from the bowl to remove the excess. A light flour coating is all that is necessary.

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Write a summary of the previous text in Chinese:
检查肝脏表面是否附着着一层筋膜，有的话就把筋膜撕掉。 将肝脏切成1cm厚的片。 将2个洋葱切成0.6cm厚的条 混合面粉、黑胡椒粉、盐。 将片好的肝脏裹上面粉。