Sofrito is used as a base for many dishes. Depending on where it comes from, sofrito can be made with different ingredients. Our tour guide at Miami Culinary Tours explained that the sofrito (the base for Ropa Vieja) we had was made with pepper, onion and garlic only and then tomato was added to make the base for the Ropa Vieja, much like the Mirepoix used widely in the culinary world. I used red bell peppers to enhance the red colour - but traditionally green bell pepper is used as well.
Chop the peppers, sweet onion and garlic finely, OR roughly chop these ingredients and finely chop them in a food processor (make sure they do not turn into puree).
Heat the oil in a non-stick pan, then add all the ingredients to the pan. Cook the chopped ingredients with about ¼ tsp of salt on medium-heat until the mix starts to turn translucent and you begin to smell the mix. Add the oregano and continue to cook further until it softens - for about 15 minutes.
Add the tomatoes and sugar and cook for a further 15-30 minutes (it could take longer, depending on the heat of your stove). Make sure to stir the mix occasionally to prevent the sofrito from sticking to the pan and burning. You want to cook it low and slow until it thickens and all the flavours come together.
Add more salt and a little bit of lemon juice to taste (and to brighten up the sauce), and stir to mix.
Store the sauce in an airtight jar or container and keep it in the fridge.