In a saucepan, combine olive oil, garlic, salt, pepper and chilli flakes and lightly saute over high heat.
Reduce heat to low and mix in tomatoes and tomato paste. Stir in celery salt, salt and pepper. Start with 1/2 cup of the brown sugar and mix into the sauce. Gradually add brown sugar, depending on acidity of tomatoes. First taste of sauce should be sweet.