Make a small cut at the bottom of each tomato skin and place them in boiling water.
Blanch them for few minutes and remove. Put in ice water.
Once cool, remove and transfer them to a cutting board and peel off the skin.
Cut the tomatoes in halves, not through the stems but horizontally and remove the seeds.
Crush the tomatoes, while retaining the juice.
Remove the basil leaves off the stalks, wash and dry them.
Heat vegetable oil in a frying pan and add the chopped garlic. Sauté until golden brown.
Add the onions and cook until soft. Add crushed tomatoes (paste, puree, juice) and half of the basil leaves. Add salt to taste.
Add sugar, ketchup and rest of the basil leaves and cook for another 25 to 30 minutes on medium heat until the sauce becomes thick and darkens in colour.
It is recommended to make it with the given yield. It can also be stored in the refrigerator.