Red sauce (base for pasta chilli and a lot else)
Fine chop onions and crush garlic, fry in olive oil until tender.
Add tins of plum/cherry tomatoes (work out which you prefer or what mix works for you)
Add a generous amount of tomato puree, a desert spoon or sugar (gets rid of the tinned taste from tomatoes,)
Bring up to heat in the same pan as the onions etc, then just simmer on a low heat stirring from time to time.
you can chop in celery, carrots to help bulk it out to choice.
Once you have this, let cool, portion and freeze.
To make pasta, just reheat, not too harshly, then add to pasta.
To make chilli, add beans (kidney, mexican whatever you can get), peppers and chilli to taste, bring up to heat and simmer until hot, the longer the cook the stronger the chilli flavour.
Oh and the original needs salt and pepper adding while cooking, but word count go ahead of me