I was wondering how you go about making your own tomato sauce. I've looked at the recipe from c2g, where Julian suggests using double-concentrate and for each part of sauce, add 2 same parts of water and then for each litre of watered down tomato sauce, add 1 tbsp of tandoori masala and let it rest for 2 hours.
Now, I don't know about you, but here the tomato sauce comes in a tube and it's not quite very precise or pratical to be squeezing it into a spoon to water it down, so I'm hoping there is a better way around this and I'm sure there is, so any thoughts would be gladly welcome

Also, your thoughts on adding tandoori masala to the tomato sauce would be welcome, as this is one of those things from the c2g book, like "bassar", that I can't quite put my finger on.
n.b: I'm referring to the tomato sauce/paste we generally throw in around the time G&G stops sizzling
Thanks