If I were you, I'd choose between 5-6 things that I eat regularly for lunch. So, PB&J, maybe a smoothie, cheese and crackers, things like that. Stop by your co-worker's desk and say in a friendly voice,
"Hi Co-Worker! I need to be able to eat at my desk, but I want to be sensitive to smells. Which of these things would bother you?" Now, if she's not totally unreasonable, she'll pick out a few that would bother her, leaving you with a few options for the one day you have to eat at your desk.
If she is totally unreasonable, she'll say that all of those things bother her. At which point you say, again with a smile and friendly tone, "Well, it's not possible for me to avoid eating at my desk on Tuesdays. So since we can't come to a compromise, I can give you a head's up before I eat and maybe you can find a way to avoid the scent. Good luck!"
And then go ahead and eat whatever you want, because by that point it will be clear that there is no way of making her happy and she is being SS.