Thanks for posting or reposting this Gary. The base sauce has the same structure as the Zaal or Chewytikka bases which is the initial boil of onions et al, then a frying stage of spices and tomato then blending and re-boil the combined sauce till the oil rises. In your version above the fried Tom mix is added before blending, in others it's added after. Not having tried every base I should be wary of making sweeping statements but this boil fry blend boil again (or boil blend fry boil again) structure seems indicative of a good base and it's how I prepared my last batch of base which has brought my own cooking on in leaps and bounds.
Having made a hell of a lot of base over the years - (and to the power of 10 since I discovered this site!) - I can only concur that this method does indeed produce excellent and consistent results. Not only that, but there's something about it that 'feels' right.
These days, whatever base recipe I'm using, the technique goes:
Oil in pot, followed by raw ingredients (onions, carrot, garlic/ginger, etc, etc).
Bring slowly up to temp to get things going, then add the salt, stir and lid on and heat down low. If I add any water, it will only be a cup or two, depending on the quantity of base being made.
Once the onions are properly cooked (soft, melting and translucent - I don't time it), I do the fry stage with the spices, blended tomatoes, and some extra garlic/ginger paste, add to the pot, and cook for a further 15 minutes or so.
Next, I blend to a smooth consistency (adding water to thin down), add some whole spices (cassia bark, cardamoms, Asian bay) and bring to a gentle simmer until the oil rises to the surface. (Time for this varies depending on the quantity of base.)
This, for me, produces the best results.
I used to be a chuck it in and boil man*, but thanks to the efforts of too many people to mention on this site I've picked up incredibly useful information and been able to develop something that puts a smile on my face every time.
So, thanks to all - and keep up the great work!
*Not saying that 'chuck in and boil' doesn't produce good results. I've just found the above better for me.