There is no real written recipe for these peppers so use whatever you like and have on hand. I learned this dish when I visited my inlaws in Sicily 26 years ago and have been making it ever since. I suggest that you use it as written the first time and then do your own thing next time. I have made this in the microwave, but you have to be careful as green peppers can get bitter. I'm not sure why. My kids were the ones that decided that red peppers would be better and now they make their own with red peppers as well. You can easily control the use of salt, but remember that canned tomatoes, olives and cheese have a lot of salt so don't add too much extra. If you can find low sodium alternatives you will have greater control.