Mix the cornflour with a small amount of water to dissolve.
Add the drained beans, tomato purée, the rest of the water plus the cornflour mixture to an oven proof dish with a lid. Cover and bake at 180C for about an hour. Stir from time to time.
When the sauce has thickened add the coconut sugar (I use about 1 tsp), the salt (I use about 1/3 tsp), the vinegar and paprika. Serve.