Do you have non-stick sheets that go on you dryer trays?
If so, spread the sauce to an even thickness and dry it.
If not spread it on parchment paper on the tray. (Test a single tray first to be sure your sauce and your parchment paper release when done.)
When it is dry (brittle when cool) put it in the blender and wizz it once or twice to pulverize the big chuncks. If it truly just sauce, versus a stew or thick soup, wizz it into near-power form. It will re-hydrate almost immediately.