I kept the passata very simple, I can add other ingredients when I use it depending on that use. Here it is
3kg tomatoes
15 peeled and roughly chopped garlic cloves
1 tbs salt
1 tbs ground black pepper
2 tbs sugar
All ingredients in one big pot and cooked for adbout 25mins. I cooled it down then passed it through a food mill. Back into the pot and reduced until thickened slightly. I ended up with about 1.2 litres of passata which I divided up then froze for use during winter.