WorldsWorst wrote:
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> Add tomato - also a little water and cook covered on a lowish heat for a few
> minutes - stirring all the time.
>
> Add the beans and cover with water to about an inch or two above.

I would add the tomatoes AFTER the beans are tender. Any acid (including that in
tomatoes) prevents the starches in the beans from breaking down as quickly as
they normally would. Adding acidic ingredients after beans have softened to a
desirable stage will keep the beans from getting much softer.

http://www.globalgourmet.com/food/eg.../saltacid.html

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