In a saucepan, heat the oil and butter on medium-low until the butter melts. Then add the bay leaf and minced garlic and saute for about a minute.
Now add the onions and saute until golden brown and soft.
Next add the diced tomatoes and cook for about 10 mins covered on medium heat until the tomatoes are soft.
Stir in tomato paste along with 1 cup of starchy pasta water, talian seasoning, parsley, salt and pepper and simmer for 20-25 mins medium low or until the sauce has thickened and reduced.
Usually the sauce will sweeten as you cook but if you want to cut the sourness add some sugar.
Tear in the fresh basil leaves and cook for about 5 mins more. That's its, Pasta Sauce is ready. Keep aside