In a large pot over medium heat, melt the butter. Add the onions and salt, and cook, stirring occasionally, until the onions really soften up- 10 minutes or so.
Stir in the minced garlic, salt, curry powder, coriander, cumin, and chili flakes, and cook just until the spices are fragrant and toasty- 30 seconds or so.
Stir in the tomatoes including their juice, and 5 cups of water. Simmer for 15 minutes.
Add the can of coconut milk and puree the soup with an immersion blender, or in batches in an upright blender. Taste and adjust with more salt to taste.
To serve, top with any of the following that sound good to you- cooked brown rice, dollop of coconut cream, lemon wedges, toasted almond slices, pan-fried paneer, fresh thyme or oregano, a poached egg, or a toasted wedge of good bread.
Recipe from http://www.101cookbooks.com/archives/a-simple-tomato-soup-recipe.html, retrieved April 2013.