In a lightly-oiled 3qt saucepan, saute onion and garlic until browned. Stir in spices and flour and continue to cook for another minute. Add vegetable broth, coconut milk and tomatoes. Bring to a simmer and reduce for 30 minutes until thick.
This was also excellent, but I'd do things differently next time. First, the spelt didn't add much, I'd just use regular flour. Second, the original recipe said to "simmer" when I think it actually meant "reduce". Whoops - I simmer with a lid on to keep the liquid in! Luckily, we could just leave it on the stove while we ate. Third, I disliked the texture of the tomatoes after boiling, so I pureed it with my immersion blender. Much better.
This sauce can be frozen though it will lose some thickness. Definitely a keeper to pour over the filling and rice for lunches.