I use peri peri sauce for grilling chicken, but it's coming out to be too sour. How can I neutralize the sauce?
There is really no way to reduce the acidity in a marinade or sauce without creating undesirable flavor compounds. Adding a base would neutralize the acid but would also produce salts which don't taste so good.
If you are making a marinade then simply add less acid to it, however if you are using bottled sauce then you have a few options to deal with the excess acidity:
If it were me I'd combine some of the above, I'd add some sugar and maybe a bit of water until it's a bit weaker.