Staff left the meat hanging for hours on a rooftop as temperatures soared to 25C so that it would dry out.
In a separate incident, a chef from the same restaurant was spotted unhooking two raw duck carcasses from the line as oblivious customers tucked into a buffet inside.
Flies could be seen landing on the meat, hanging close to flocks of birds jostling in the trees above on the roof of the N.C Rev in Gravesend, Kent.
Stunned resident and former chef Paul Nelder, 23, said the meat was hanging for at least two hours on Saturday.
'I've never seen anything like it in my life. On one of the hottest days of the month, I saw this massive raw carcass, hanging there in scorching heat,' he said.
'It remained for two hours before being removed, but as far as I know it could have been there longer.'
He added: 'I have worked in a few different restaurants, canteens, fast food places and have seen some things but this tops the lot.
'Why do they need to hang this raw meat outside, can it not be left inside the kitchen? For hours this is left outside in the heat, attracting pests like flies and pigeons.
'We have netting up at our kitchen window because we are always getting flies and pigeons trying to get in.
'We see mice running around outside and this meat hanging from the washing line can only be adding to the problem. I just hope this is not being served in the restaurant.'
Mr Nelder dismissed the first incident as a one-off but called in the local press after seeing what appeared to be duck carcasses back on the line on Monday.
A photographer watched from his flat window for over an hour before a member of the kitchen and waiting staff removed them.
The manager restaurant manager insisted it was not a regular occurrence and the meat was being prepared for staff rather than customers.
Bee Nyew said: 'It's not regular, the head chef was not here. The meat was not served for the customers, it was just for the staff.
'The chef wanted to do it crispy so he put it there to dry. Saturday was the Chinese mid-autumn festival so we did that for our staff only.
'I have spoken to the inspector today about this because the food is not served to the public it is no problem for the council.
'We are very busy and we always take care of our hygiene. Everything is high quality and everything is hygienic.'
Gravesham Borough Council said they would closely monitor the eaterie for the shocking practice.
A council spokesman said: 'Gravesham Borough Council's environmental health officers visited the premises on Tuesday and put to them the complaint received and the photographs from the Gravesend Reporter.
'The manager said that the duck being hung on the washing line was for the staff's own use, not for public sale.
'As a result of the complaint, though, the manager said the practice of allowing staff to do this would be stopped immediately.
'Under the circumstances, the council will take no further action but will continue to monitor this and all other restaurants and takeaway outlets.'
