I thought sage and onion stuffing was served with pork (and poultry), are you thinking of 'forcemeat stuffing' which is usually made with sausage meat but can be any combination of ground meat, chicken, spices, veggies, even fish?
If that's the case then there are so many variations I can only suggest you try google, just make sure you have plenty of time to go through the thousands of responses!
Cheers
CoR