The onions that I used are asda large onions, about 90mm diameter (they do them in size not weight). I also used smaller ones, but kind of guessed how many to make about 15 of the larger sized ones, so probably used about 25 onions in total, but they would have been the equivalent of 15 90mm diameter ones, if that helps. I have nothing to hand at the moment to weigh one I am afraid. I find that you can get really large onions that are sold in packs of two, but the ones that I refer to are sold in bags of three. And please feel free to bombard away. I really just tried to follow the recipe to the letter as much as possible, allowing for them all to cook, before blending them all up into a really fine mix, I made sure that they were well and truely blended! Then I recooked and allowed to cool. I have made two loads of this base now, and the second time turned out just the same as the first (although I added the chilli powder the second time but not the first, but I like my curries hot). I didnt chop everything up really tiny, as you can see from the pictures, as I figured that as long as everything is cooked, you are going to blend it up anyway, but I kept the carrots and the celery, and even the peppers about the size that you might chop them for other more usual cooking dishes, sunday roast etc. The onions I just chopped in half, and then sliced into about five or six slices. The corriander I chopped up quite finely. I am not sure if I mentioned already, but where it said 600-700ml of oil, I used around 600ml of oil to start with, not 700, but that is down to personal preference I guess. I hope that helps, but please feel free as I said to ask away any questions that I may be able to answer for you.