You can stir-fry walnuts with a small fire, as long as the skin is hot. Then let it cool and peel it off. It's easy to rub the skin inside with your hands.

This astringency may come from walnut skin, that is, the thin brown or yellowish skin on the surface of walnut, which will not cause harm to the body. It's easy to get rid of this thin skin. When the walnut kernel is soaked in hot water, the skin can be easily peeled off when the water gets warm. However, walnut skin is also rich in nutrition. After walnut kernel is peeled, its nutritional value will decrease. If you really don't like the taste but don't want to lose nutrition, you can also make walnut kernels into amber peach kernels or add them to dishes for cooking.