Jarred salsa has three hallmarks — slightly sweet, a tangy vinegary bite, and soft cooked veg. Raw pico de gallo will never hit that note. You have to simmer it, and you have to be honest about the sugar.
why it works
Made at home you control exactly how much sugar and salt goes in, which is where the shop-bought jars do all their damage. Half a teaspoon of honey across a whole jar's worth is nothing next to what a commercial salsa carries.
Splash of oil in a small saucepan over medium heat. Fry the diced onion and pepper for 3–4 minutes until soft. Soft cooked veg is one of the three things that makes jarred salsa taste jarred.
Stir in the tomato paste, tinned tomatoes, vinegar, sugar, garlic powder, salt, cumin and the jalapeños or chilli.
Simmer gently on low heat for 8–10 minutes so the tomatoes break down and the flavours meld.
Taste it. If it doesn't taste sufficiently jarred, another pinch of sugar and a drop more vinegar will get you there. Serve warm, or fridge it for ten minutes.