Saute peppers in some olive oil until al dente about 20 mins. In the mean time blend or grate your tomatoes

Remove peppers and in same pan add some olive oil garlic and tomato. Allow to simmer until reduced by half.

In a small glass fill half spirt vinegar and top up with water.

Dilute a spoon of corn flour to vinegar mixture and put into tomato mixture. Incorporate well and put on low heat. Add peppers and allow to simmer until mixture thickens and peppers soften