lexycat wrote:
Thank you all for your suggestions! This is new to me, so I appreciate the help. I want to try the tamarind and umeboshi paste. I have never had either of them, so what is a quality brand?
Well, you're unlikely to find more than one brand of umeboshi paste unless you live in a large Japanese neighborhood, so take what you can get. For tamarind, brand doesn't matter. The question is whether you get pressed tamarind pulp, or liquid tamarind in a can. The pulp is dehydrated and keeps pretty much forever (6 months out, 2+ years in the fridge), but has to be sliced, hydrated and filtered before use. The liquid is ready-to-use, but doesn't keep very long once opened. Of course, if you're using it all the time, then you'll probably go through it a lot faster than I do.
Note that tamarind is sweeter than tomatoes, so adjust accordingly.
I'd also look at some of the milder citrus. Meyer lemons, for example, can add a nice bit of tartness. Or if you can get your hands on them, dried limes (look in arabic groceries).
To substitute for small amounts of mashed potato in a recipe: stale bread soaked in milk.
Also: sweet potatoes are not nightshades. They're members of the Morning Glory family (yes, really).