In response to the question about whether working in factories that manufacture canned pork and in nightclubs or other centers of corruption is permissible or not, Ayatullah Khamenei says:

Making a living off of haram acts such as selling pork, liquor, establishing or managing nightclubs, centers of corruption and gambling and drinking and the like, is impermissible and the money made from such is haram and one who receives money from it, doesn’t become owner of the money [1] . [2]

Also, regarding selling najis substances (eyn al-najis) such as liquor, pork, etc. and working in places that sell them, he says: “The sale of intoxicant alcoholic beverages and haram foods and working where they are sold and taking part in their production and sale and taking orders in this regard, is haram, making no difference whether one is an investor in such a place or just a plain daily worker, whether only haram goods are sold there, or halal things are also sold, whether one gets income for such a task or just works for free, whether one’s co-worker or employer is Muslim or not, whether the haram thing is being sold to a Muslim or non-Muslim, to put it in general terms, it is wajib for every Muslim to abstain from the production and buying and selling of haram food products for the purpose of consumption, and to also stay away from the sale of alcoholic beverages and making money from this means. [3]

To conclude, it is haram and impermissible to prepare foods to serve, that contain alcohol. In general, working in such restaurants is haram.

For further information on the rulings regarding this topic, you can refer to the section on haram jobs and transactions, the chapter on the sale of najis substances. [4]