Boil orzo until al dente, then drain.
In the meantime, preheat a large pan over medium heat. Saute the onion in olive oil with a pinch of salt until soft, about 5 minutes. Add garlic and saute for 30 seconds more.
Add rosemary, wine and sundried tomatoes. Season with salt and pepper and turn the heat up to bring the sauce to a simmer. Let simmer until reduced by about half, 5 minutes or so.
Add broth and yeast and warm through. Then add the spinach in handfuls, letting each batch wilt before adding the next. Cook until spinach is thoroughly wilted then turn the heat off, add the orzo, mix well, and serve topped with tempeh crumbles.