Stir in 2 teaspoons curry powder, 1 teaspoon red curry powder, 1 teaspoon coriander, 1 teaspoon cumin and ¼-½ teaspoon red pepper flakes and cook 30 seconds, stirring constantly. Add 15 ounces diced tomatoes, 28 ounces plum tomatoes with juices from the cans, and 5 ½ cups water (or broth). Simmer for fifteen minutes, then puree with a hand blender until smooth. Now your tomato soup is finished and could be enjoyed just like this for a simple, delicious soup.