When i marinate pork with spices and vinegar , can i also add the sauted onion paste overnight with it?
The separation of the processes is about the chemical reaction between the spices and the pork first. The onions add a different set of chemicals and oils that are unwanted during the marination process. So, no, the taste will probably be different as the onions will change texture overnight, and the addition of the chemicals and flavors from the onions will change the flavors that are absorbed into the meat.