Help identifying a plant

Hi. I found a volunteer tree or shrub growing in my back yard and hope someone can help identify it for me.
The pictures are posted here:
It is doing quite well on my sunny window sill. I live in California, zone 9b, Sunset zone 15.
The leaves are (I think this is right) pinnate, arranged opposite, elongated lance-shaped and toothed. Stem is woody. Closest matches I could come up with are sumac, jacaranda, or mountain ash, although none seem exactly right.
Any ideas? TIA.
- Dewolla Stepon
-- - Dewolla Stepon 262//202
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