Step 1) Heat oil in a large, deep saucepan or Dutch oven over medium heat.  Add onion and cook until soft, about 3 to 5 minutes.  Add garlic, mushrooms and green pepper; cook 3 to 4 minutes.  Stir in tomato paste, tomato sauce, diced tomatoes and spices.  Simmer 15 to 20 minutes, stirring occasionally.