Peel the skins from the tomatoes and or just put them straight through a press to separate the skins and seeds. If you don't have a press, mash the tomatoes or blend in a blender after peeling (blanch them for a minute in boiling water to make it easier).
Leave the mixture in a gauze to drain for 2-3 hours. Then heat the oil on the stove with the sugar and add a little vinegar to taste. Pour in the drained tomato mash and boil on low heat, until thickened.
Add 1-2 crushed aspirins at the end. Distribute the mixture into jars or bottles and close them. Sterilize for 10 minutes.