This homemade ketchup is simple, economical, and way healthier than what you find in the store. It's sweetened with either dates or stevia, so you avoid all the sugar or HFCS that you find in the stuff from the store.
After the tomatoes are roasted, add the sliced onions and cloves of garlic to the tomatoes and roast another 15 minutes and then let cool.
After the roasted vegetables are cooled, add the tomatoes, onions, garlic, dates and all other remaining ingredients to a high speed blender such as a Vitamix and blend.
If mixture is too thick for your liking, add a bit of the reserved water from soaking the dates to the mixture (or more apple cider vinegar if you prefer a more tangy ketchup).
Chia powder: Chia powder (aka Chia flour or ground chia seeds) is used to thicken the sauce, and can be omitted. You can typically find this at health stores or larger specialty grocery stores (like Whole Foods). It can also be made in a high speed blender, such as a Vitamix, using the dry bin. Dates: You can use stevia instead, or maple syrup. The correct amount will depend on the brand of stevia, or if you make your own. Add small amounts while blending and keep adding to taste - start with 1/8 tsp stevia or so.