In a small saucepan, boil some water and cook whole tomatoes till soft to touch.
Remove, cut the end and blend them into a puree and keep aside.
If you using canned tomatoes, just puree the contents of the can and keep aside.
Heat 3 tbsp of olive oil in a large pan.
Add the finely diced garlic and after a few seconds, add the finely diced onion.
Saute the onion til it turns light brown.
Add the chili flakes and red chili powder and mix well.
Add the tomato puree and mix well. Add necessary amount of salt.
Add ketchup.
Cover and cook on a low flame till oil rises to the top.
Add oregano and mix well. If the sauce is too thick, add a little hot water.
Add the bell pepper, if using. Mix well.
Cover and cook for a few more minutes, switch off and keep aside.