In my opinion, the best way is to add cornstarch to reduce the water and also keep the original taste.
Since vinegar can be evaporated very fast and a better choice is to add the vinegar after you have cooked the cornstarch with marinade.

Hi quddous

I am so glad that you are going to Chengdu, which is a real Food Paradise!

If you are visting Chengdu, you can have a try with Sichuan Cuisine with most famous spicy food like hot pot, mapo tofu etc.

My suggestion is that try to visit the places with lots of people even you have to wait for some time. it is just too many places to mention. I recommend eating hot pot and some sichuan cuisine.

Besides, you can also visit the food street to have some local snacks. Such as a place named as Huang Cheng Ba (Imperial palace dam 皇城坝).

If you want to know basic about food in Chengdu, you can check some recipes I made in my blog http://www.chinasichuanfood.com with most of the dishes from Sichuan Cuisine.

ops, late again. But I hopt to explaine something. This type of Doubanjiang is a extended product of traditional pixian douban. It is Doubanjiang in red chili oil.
There are generally two differences about this type and pixian doubanjiang.
Firstly, it has a shorter fermentation time than traditional pixian doubanjiang
Secondly, chili oil is added into doubanjiang.
It is a ready sauce and thus you can use it in cold mixing dishes or in dips.
But you should use Pixian doubanjiang if you are cooking sichuan hot dishes.
I hope that this can help .

In fact, you can use Lee Kum Kee Chili Bean Sauce to replace the mentioned spicy bean paste. Chili Bean Sauce is similar to Doubanjiang with some soy beans added. But the taste is quite similar.

Hi paulj

I am sorry for that misunderstanding. And thanks very much for pointing this out for me. I am only familiar with Chinese cuisine.

In fact, there is a way. I do think that many people need this method. And it is really simple. Just boil the peppers in boiling water. Additionally, the color will also become nicer. I hope that this can help. Have a try! Good Luck.