I'm wondering if 1) I could substitute any jam for the blueberry mixture and 2) Is there another fruit that would work well?

It seems like the blueberry swirl in this recipe is a bit thinner than a typical store-bought jam, so you could try whisking in some citrus juice to thin it to "swirly" consistency. I imagine most fruits would work well...tahini is nice and nutty so something sweet and a bit tart to cut the fattiness. Apricots are used often in middle eastern cuisine so I imagine they'd have an affinity for each other. I also just happen to love apricots. The "swirl" recipe seems pretty simple and I would imagine most juicy fruits would do well.