Drop them into boiling water for 30 seconds, then into ice water.
Peel off the skins, then chop roughly.
Cook Everything Down:
In a saucepan, sauté the onion and garlic in a bit of olive oil until soft (about 5 min).
Add chopped tomatoes, vinegar, sweetener, salt, and spices.
Simmer uncovered for 30 minutes, stirring occasionally, until thickened.
Blend & Strain:
Let cool slightly. Blend until smooth using an immersion blender or regular blender.
Strain through a fine mesh sieve for a smoother texture directly into the pot you were using to cook.
Simmer Again:
Return your pot to the stove and simmer until it reaches ketchup consistency.
After about 20 minutes, stir in the tomato paste the simmer for another 15 min or so. This process should thicken the sauce. Keep in mind once it’s in the fridge, it will continue to thicken.
Cool & Store:
Cool completely, then store in a clean jar in the fridge for up to 3 weeks.