I can completely understand your frustration!!!

Perhaps a sandwich? Even if it's just jam, or vegemite or cheese.

What about a little snack tray of sultanas, cheese & crackers? I know it's not the healthiest, but it's something.

IMO, I think you just need to get her to start eating ANYTHING at dinnertime, once you have it established that she will actually eat at dinnertime, then I would start getting strict on what it is she consumes (vegies, meat, etc...). I think the trick first is to get her body used to eating at dinner time & then start introducing a 'suitable' dinner. KWIM?

Good luck!