firstly, blanch the tomatoes in enough water. take well ripped tomatoes.

further cover and boil for 3 minutes or till the skin of tomatoes starts to separate.

cool down the tomatoes completely, and transfer to the blender.

puree the tomatoes without adding any water.

using a filter, extract the tomato puree separating seeds and skin of tomatoes.

further, stir and mix well.

boil the mixture well.

make sure to stir occasionally, to prevent from burning.

further continue to boil for 10 minutes.

add in ½ tsp chili powder, 3 tbsp sugar and salt to taste.

keep stirring till the tomato puree thickens.

also cook the mixture till the water is evaporated completely, and turns thick.

and in 3 tbsp vinegar, as they act as preservative.

mix well and check for seasoning.

finally, transfer the tomato sauce or tomato ketchup once cooled completely.