Rose hip tea.
Rose hip tea is deep red and sour because of the roselle, not because of the rose hip.
I've dried rose hips (the fruits of wild roses). Sliced them into halves, removed the seeds, and dried them. And made tea out of them.
So I just read that rose hips "impart a lovely, garnet red color and a tart taste to your tea". Umm. No, that's not the rose hip, that's the roselle (Hibiscus sabdariffa) you'll find in all commercial rose hip teas.
Or at least, my homemade rose hip tea, with nothing but dried rose hips, didn't taste of anything and was a pale pale light red in color.
Of course, if you've had better luck, tell me what you did and I'll check things out, come autumn.