Not sure why everyone is arguing about how big his cups are - worry no more, "the truth is out there" in the video.
He added 400g of tomato paste, let's be picky and say 380g because of the amount he left in the can. At a density of around 1.06 grams per ml that's near enough 360 ml of tomato puree in the pan. About 50ml of oil went in at the start, plus spices which I'm gonna pretend have no volume (let's be sensible about this!) and 10 or 15ml of G&G paste.
That's it. Let's say 425ml of ingredients and the rest of the finished volume has to be the water he added. Allowing for a conservative evaporation factor of 20% (likely higher than that after 10 or 15 mins bubbling away on a commercial range, but let's be conservative) and I'm going to say there was 850ml of total volume (ingredients plus water) at the start of the cook.
Ergo, added water must equal at least 425ml, likely a bit more. Since he says he added two cups and a cup measures 250ml I'm going to say he does know what he's talking about.
