I recall one liquid vitamin in the Nature's Harvest section of HEB that I didn't find palatable, but I don't remember the brand. (Thomas wouldn't touch it, but Thomas won't touch vitamins in any form. I'm convinced that one of the vitamins in the mix has a flavor that he dislikes.)

Liquid chlorophyll might be worth a whirl too; it's not _bad_ tasting per se, but it's pretty weird. (Then again, it might have the side effect of turning her off veggies....)

Would a teaspoon of straight molasses work?