We were mostly pretty passive/aggressive on this thread in our replies. I think it was that it was Halloween that brought out the ghoul in me.
I like Gaj's approach about kissing her azz with the 'how do you make it?' It's up to you if you'd make it the way she says or the way you do anyway. What are we really talking about here one scoop of coffee more or less? This woman could just add a little hot water to her cup and there'd be no problem, duh.
But if you butter her up by treating her with such importance, it will stroke her ego and she will like you better and not make trouble for you at work.
My dad makes undrinkably strong coffee. When he makes it for me I ask him to make it weaker. If I was at work and the coffee was truly undrinkably strong (like he makes) I would either just add more water to mine and shut up or ask the person who made it to make it less strong next time.
This woman is rude and nasty to have humiliated you like that in front of the whole office. I don't think telling her how that hurt you will help you. I think she is the type who will then really be out to get you. There are just horrid people like that. It's best not to tangle with them and avoid them when possible. You have to act like it doesn't bother you at all, how she is complaining about your 'incompetence' in front of the whole office.
Grace is the key to winning this.
I guess if I were you in this situation, when she was complaining to everyone how undrinkable it was, I'd ignore her then take a quick vote to see if everyone thought so. They might be so scared of her that they'd all say yes. Then I'd make the coffee weaker next time.
This is such a dumb predicament, over coffee! But a reality in the workplace. I feel for you in having to deal with this woman. There is one of her at every job!