Shanghai local cuisine is characterized by heavy oil and red sauce, that is, soy sauce is added without salt or less, but because the taste of soy sauce is not very salty (unlike in the north), it is sweet, so it will feel a little sweet when eaten.

There is also a reason for the heavy oil red sauce. Shanghai originally gathered people from all over the world, forming many kinds of dishes, each of which maintained its original characteristics. However, most of the local dishes used to entertain street vendors and pawns, so they lacked oil and water, so they would put more oil to attract business. Moreover, these people are doing heavy work, sweating a lot, and need to add salt, but they can't see the salt, so the merchants come up with soy sauce, and the color can be seen (how smart Shanghainese are). This is the characteristic of this dish.

At present, soy sauce is not very salty at first, so it tastes sweet, but the characteristics of heavy oil have been maintained.