Place a medium-sized saucepan on a medium-high heat with the olive oil. Once hot enough add the red onion and season with salt and pepper then cook for 5 minutes until softened.
Add the garlic and fry for a further few minutes.
Next add the red wine vinegar and cook out for a minute before adding the balsamic vinegar.
Add the remaining ingredients to the saucepan, place the lid on and simmer gently for 10 minutes.
Transfer the contents to a blender and leave to cool before blitzing to a smooth sauce.
Recipe by Food & Fitness Always at https://foodandfitnessalways.com/recipe-homemade-tomato-sauce-8946/